How to configure the keyserver for Zemax network licenses (Zemax legacy)

This article explains how to configure a license keyserver, a FAQ and some troubleshooting tips for Zemax licenses with a license number in the format L1XXXXX either a softkey license or a Red USB license.

If you have purchased an Ansys license and are configuring a license server, refer to this article instead.

If you are an end user trying to access an existing network license server rather than setup a license server, visit Configuring Zemax applications to access a Zemax network license

Authored By Don Dickinson


This article explains how to configure a license server and client machine for use with an Opticstudio, OpticsBuilder or OpticsViewer network license that uses a Red USB license or softkey. These use a license number such as L100000 or T100000. 

Before proceeding, please read:

If you have purchased an Ansys license and are configuring a license server, refer to this article instead.

If you are installing a license server that uses a black USB license (license numbers from 22000-40999) see this article.


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Note that the network softkey or red USB license is worth the full value of the software. We recommend that you ensure the network key for its full replacement value, and that the keyserver machine be kept in a secure room. See the Zemax Licensing Policies for details on both perpetual and subscription licenses.

Zemax network licenses make it easy to receive support renewal updates as they only have to be applied on the server machine. This also means the seats can be shared among a team without using transfer codes or trying to keep track of physical USB dongles for each user.

The Red USB network key has the licensing information embedded in it. The softkey has no physical unit -- the license itself is attached to the keyserver computer through software.

License check-in/check-out for offline use of a license seat is supported with Softkey licenses, but not the Red USB key.


Preparing to install the license server 


Before installing the software, there are some simple concepts you must understand. The network key is installed on a machine called the keyserver. This can be a real machine or a virtual one. The server hosts the license key and the software service that makes the license available over your network (LAN). The keyserver can be any Windows machine on the network.

There is no Linux support for the license server. It can be installed on Windows 7 Service Pack 1, 8.1, or 10 or any Windows Server 2008 R2 SP1 or newer Server operating system. Note that "Core" (non-GUI) versions of Windows Server are not supported.  The server requires ~500MB drive space free for the software and only requires the same minimum RAM the OS requires to install. 

Client machines are the machines that will run your Zemax software or and use the network license. The client machines must be able to ping the keyserver in order for the server's license to be seen.

Zemax legacy licenses use the Thales (formerly Gemalto) Sentinel LDK license technology and communicates on port 1947 on your network.  


Tip: You cannot run multiple client users of OpticStudio on the key server itself or multiple users on client machines. You may have one user on the server or on each client machine. This is due to the instance limitations and the way the licensing is designed to assign network seats to client computers. See the FAQ at the end of this article for details.


Installing on the server machine


The first step to configuring your network license is to properly configure the keyserver machine that will host the license. Doing this requires three steps: installing software and activating the license, checking the Windows firewall, and configuring the keyserver settings. The following sections describe these steps in detail. Note that in order to properly install the keyserver software, you must be logged in as an administrator on the key server machine.


Install and activate the license software


To install the license software and activate your license, take the following steps. 


  1. For installations on machines with Internet access, the Zemax license manager software will download everythnig needed. If your server is without internet access, you will need to first download and install the .NET Framework from Microsoft. As of Jan 2021, the minimum .NET version required is 4.8 but you may install a newer .NET framework if you like. Then proceed to step 2 and install the Zemax License Manager.

  2. Navigate to your profile page and log in. Open the "Zemax OpticStudio" (NOT Ansys OpticStudio) section. Download and launch the Zemax License Manager (ZLM) installer. This application will allow you to view, manage and activate or transfer a license, as well as update your license when renewed in the future.

    You may accept the default options or choose an installation folder.

    Tip: If you are upgrading over an older version in the same folder, all settings and licenses will be retained. 




  1. Activate your license

    Note: Starting in May of 2019, Zemax begin shipping the Zemax License Manager Version 2 (ZLM V2), with a different user interface.  The instructions below cover the newer versions of ZLM as the old versions have been phased out and most new licenses require the newer version.
  • For Red USB network licenses: These require no activation. You may plug in your red USB dongle. The key should light up with a red light if it is working properly. If the key does not light up, you may need to refer to the "repairing the license runtime" in "How to troubleshoot red or green USB license issues" article. If the key is lit, move down to Step 4.

  • Softkey licenses: If you only received an activation code, and the server is connected to the internet, start by opening the Windows Start menu...Zemax License Manager...Zemax License Manager. If you have a softkey license and your server is not connected to the internet: Note that activation codes starting with "ZU" cannot be activated offline. otherwise please visit this article for instructions to activate your softkey license offline. Then come back to this article and move down to step 4 "Verify your license" to complete the server configuration.

    If you are completing a license transfer from another machine, use the "Receive License" tab instead and use the transfer code you have been sent. 

  • Softkey activation - Select New License, enter the License Number and Activation Code. If your software requires a Zemax account login, two fields will automatically be displayed to enter your Zemax email address and password. Once activation is complete, you will receive a confirmation message that your software has successfully activated.

    Move down to step 4 "Verify your license"

    TIP: If you get a "not authorized" error, find the License Administrator located in your Zemax Account profile page and ask them to add you as an "end user" of the license. That will authorize you.





  1. Verify your license is installed and working. After activation, you will be taken to the View License section. Verify that the Product, Support expiration, and Seats: Total match your activation email or purchase order.

    IMPORTANT: After completing activation and verifying your information, we recommend reading the Zemax Licensing Policy. It provides details on how softkey licenses are locked to the machine, tips to avoid losing it, backing it up, and our policy on lost keys. 

    Move to the next section "Check or open the Windows Firewall". 


License Information







Check or open the Windows firewall (server only)


The next step in the installation and configuration process is to check the Windows firewall. Normally the installation process opens the Windows firewall for you automatically. This section will tell you how to verify that it is configured properly.


  1. Open the Windows Firewall settings by clicking the Windows Start button and searching, "Firewall."
  2. Select the Windows Firewall app.
  3. Select "Allow an app or feature through Windows Firewall."


Allow an app or feature through Windows Firewall


  1. Check the list of applications. If “License Manager” or "Sentinel License Manager" is already on the list, then you may move to the next section of this article: Configure keyserver settings and security. If not, move to step 5 of this process to add it. 




  1. Click "Allow another app." If "Allow another app" is greyed out, select Change settings to enable it.




  1. Click Browse and open the C:\Program Files (x86)\Common Files\Aladdin Shared\HASP folder.
  2. Select the hasplms.exe file from the list and click Open.




  1. The Zemax License Manager will appear on the Add an app window. Click Add to add the License Manager to list of exceptions. 




  1. The check boxes next to License Manager specify which type of network includes this exception. You may check any (or all) the boxes for Domain, Public networks, and Private networks. public networks are excluded by defaut for security reasons.

    Tip: If the computer is not joined to a domain, the Domain option will not show up. 




  1. Ensure port 1947 is not blocked on your network firewall both for UDP and TCP, and that you can "ping" the IP address or name of the key server machine from other machines. Consult with your IT or network department if you are not sure.  


Configure keyserver settings


​The final step in configuring the keyserver machine is to configure its settings and security. Click on Launch Sentinel Admin Control Center (ACC). This is located at the top of the Zemax License Manager (Classic) or under Troubleshoot (ZLM V2). You can also get to the Admin Control Center by opening a web browser and navigating to http://localhost:1947.  

This will open your web browser to the the following page. If this page does not open, see the "repairing the softkey runtime" section of "How to troubleshoot softkey license issues."


Click Sentinel Keys to see your installed Zemax license(s). Licenses can be identified by the Key ID field, which is also present in the Zemax License Manager. Note that Gemalto/SafeNet do provide licenses for other software, so you may also see non-Zemax licenses on this page. You can identify Zemax licenses using the Vendor field; Zemax's Vendor number is 114811. 


After identifying your license, you should be done with the basic server setup! If you have troubles with any of this process, you may contact Zemax support for additional assistance. For client configuration, proceed to the next section for client configuration. 




If you would like to further specify your server settings and security, select Configuration. You will see six tabs used to configure it. By default the licenses are available to anyone within your network.

There is also no password or other blocks on changing settings in the Admin Control Center from other computers by default.

You may configure security settings, log license usage, restrict users / computers from the license, and configure license Check Out so client machines can use the software offline.

For full details and instructions on the above topics, refer to How do I monitor and control usage of the network license?


Now that your server is configured, move to the next section Adding End-users to the license


Detachable licenses


Adding End-users to the license

If you have activated a subscription license (subscription is normally in the Product Name in your activation email), and the "activated" checkbox is enabled in the Zemax License Manager, you are required to add end-users to the license. End users will get a Zemax account and be authorized to download the software, use the license as well as open Zemax support cases or phone calls.

Perpetual licenses do not require assigning end users to use the network license. However, they still need to be associated as end users of the license. This is required to get them a Zemax account so they can download the software and be authorized to open Zemax support cases or phone calls.

The License Administrator (who by default is the one who originally received the activation email) can add end users to the license. Adding a new end user will automatically send them a Zemax account invitation if they do not have one.

See this article for detailed information on license administration. Here's how to add end-users. If you are not the license administrator, you can find who the License Administrator is within your Zemax Account profile page.

Once your end users are assigned you can setup OpticStudio on a client machine. See the next section or the article Configuring Zemax applications to access a Zemax network license


Configuring the client machine to find the license

To configure client machines to find the Zemax license server, see Configuring Zemax applications to access a Zemax network licenses .

If end users need help to access the license server, please provide them the server's machine name and that link. 


Frequently asked questions and issues


Can I have multiple users run OpticStudio on the license key server machine?


OpticStudio network licenses are designed using a client-server model. The key server is intended host the license itself, and the licensing assigns 1 license seat per machine. Also, OpticStudio is designed to allow a limited number of instances per machine (2, 4 or 8 per machine depending on edition and license type). For more details on how instances work see FAQ on opening multiple Opticstudio instances

The key server can run a copy of OpticStudio for one user if you wish. Just be aware that using OpticStudio on the server for long optimizations or raytracing may tie up the CPU and may interrupt the license process for client machines.

As a workaround to allow more than one user to use OpticStudio on a single machine and allow more instances per user, you could install virtualization software such as VMware, then install Windows and OpticStudio within it. This also would allow you to limit RAM and CPU usage for each user.


Do I have to worry about losing my softkey on the key server in case of hardware failure, theft, or a reinstall of Windows?


Yes. This is because the softkey license is moved to the machine during install and locked to the machine. It works offline after install so cannot be remotely reassigned or disabled. Because of this even a software-based license can be lost and we therefore have a limited replacement policy.

We recommend reading the Zemax Licensing Policies. It gives details on how softkey licenses work, tips to avoid license loss, backing it up and our policy on lost keys. Both the policies for perpetual licenses and subscription ones are covered here. Feel free to email if you need to know the policy for your particular license type or have any questions. 


How do I configure multiple client machines with the server address, so users don't have to enter it themselves?


Normally, client machines will find the key server without entering the server name into the settings as long as they are on the same subnet. However, if you want to preconfigure the clients with a specific server name, or other settings, please see this article for details.


In the Zemax License Manager, there are fewer than the total number of available seats I expect to see. Why?


First, check on the server machine to identify who is using the license. Look at both "Sessions" \(license seats in use while the application is open) and checked out (detached) licenses (licenses used offline). For instructions to view both, see How do I monitor and control usage of the network key?.

If the total number of seats is still not what you expect, this typically means that the server has not properly released a session after OpticStudio was closed. To resolve this, you can restart the Sentinel LDK License Manager service


I checked out a license seat for use offline. When I restarted my computer, it was no longer available in the Zemax License Manager. What happened?


This is an issue that was discovered with OpticStudio 17.0 through 18.1. The vendor of our softkey licensing software released an update that addressed this issue. It was included in Opticstudio 18.4. More details on this issue in this article 


Client machines will not find the license server, or hang on the OpticStudio "splash screen" indefinitely. What can I do?


First, make sure that the firewall exception on the server is configured per the server setup instructions above. Once you are sure of that, check the client machine has specified the name of the server in the Configuring Zemax applications to access a Zemax network license article. If that is done, then your security software may be blocking access to the license software. We have seen both Trend Micro and McAfee block this.


If you use Trend Micro, check its scan logs to see if either the HASP_RT.EXE in the OpticStudio installation folder (normally C:\program files\Zemax OpticStudio), or HASPLMS.exe in C:\windows\system32 has been blocked.


If you use McAfee Enterprise, it's HIPS (Host Intrusion Prevention System) feature can block this. You can temporarily turn off HIPS to see if this is the case. On the client machine, perform the following steps: 


Right-click the McAfee icon in the system tray (by the time displayed at the bottom right). The Mcafee icon is normally a red shield with an M in the center. Navigate the menu to the Disable option. Select Disable HIPS protection. If this works, your IT department can whitelist the hasp_rt.exe process to fix it permanently. This file is located in c:\program files\Zemax OpticStudio.




Addendum: migrating your network license to a new server


This section provides a recommended procedure to move to a new server with minimal downtime and configuration. Note that if client machines have a checked out license seat at the time the license is moved to the new server, it will not affect them, as the checked-out licenses simply time out automatically. 


  1. Install the Zemax License Manager software on the new server following the process at the beginning of this article. 

  2. Copy the HASPLM.INI file from the current server to the new one. This file contains all the server settings from the Admin Control Center (user rules, detachable license settings, password, etc., as described in "How Do I Monitor and Control Usage of the Network Key?"). It is located in C:\Program Files (x86)\Common Files\Aladdin Shared\HASP.

  3. Transfer the license from the old server to the new one. If using a Red USB license you may simply plug it in. If using a softkey license, follow one of the guides here: "Transferring a Zemax Softkey License" and "Activate or Transfer, a Zemax Softkey License Without Internet Access."

    Note that there can be no active client sessions of the Zemax software open when transferring, so this is best scheduled after hours. To check if there are any open sessions and what machine is using Opticstudio, see this article: How Do I Monitor and Control Usage of the Network Key

  4. Test the license server is working with an OpticStudio client machine. If you need to test the new license server before moving the license over, you may email They can provide you a 2 week temporary network license you can use. Note that you must have an active support agreement to receive a trial license.

    If moving a softkey license, test the transfer process between servers with the trial license to make sure it works and get used to the process.

    TIP: After you are done with the trial license test and have moved the active license, you will want to remove it from the server to prevent users from accidentally using it after it expires. The easiest way to remove the trial license is to just transfer it away and discard the generated transfer code or h2r file.

  5. Let the users of OpticStudio know they may need to modify the settings on their client machines with the new server IP address or machine name. You can provide the new server information and a link to the instructions in this article: "Configuring Zemax applications to access a Zemax network license."  Alternatively you can provide them with a modified HASPLM.INI file with the new server information per the following article: "Automate Client Computer Configuration for Softkey and Red USB key Network Installations."


Addendum: restarting the Sentinel LDK license manager service to fix issues


Restarting the Sentinel license manager service on the license server is useful if it's not practical to restart the entire client or server computer, and can be used to fix the following issues:


  • The license server or clients are not able to see the softkey license in the Zemax License Manager 
  • You change a setting on the keyserver and it doesn't take effect even after submitting changes
  • A license seat fails to check out on the client even though the "detachable license" feature is enabled on the server.
  • Releases sessions showing on the server that are no longer actually in use. Note that this does not release checked out licenses.


You may either open the Start menu, and search for services.msc, or open Control Panel...System and Security...Administrative Tools...Services and right-click on Sentinel LDK License Manager and select Restart.


Sentinel LDK License Manager





If you are a network administrator and would like to easily configure multiple client machines to use the same keyserver settings, see "Automate client computer configuration for softkey and Red USB key network installations" for more details. 




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