Configuring Zemax applications to access a Zemax network license (Zemax legacy)

This article explains how to configure a client machine to use a Zemax network license for an OpticStudio, OpticsViewer or OpticsBuilder legacy network license.

Authored By Don Dickinson

Before proceeding, please read:

This procedure only applies if you have been assigned as an end user of a Zemax license number in the format L1XXXXX or T1XXXXX. If you are trying to use a license server that uses a black USB license (serial number 22000-40999 see the "Configuring the client machine" section of this article.

If you are using Ansys-licensed versions of Zemax software, see Configuring Zemax Applications to access an Ansys license.

Installing the software

  1. Ensure that you are logged in as an administrator on the machine, and are connected to your organization's network directly or via VPN.

    Download the latest copy of OpticStudio (or the appropriate Zemax product for your license) from the Zemax downloads page page and install it. Be sure NOT to install the Ansys version as they are not compatible with the Zemax legacy licenses. The site requires a Zemax account to access downloads. You may register upon getting to the login page if you need an account.
  2. Once installed, open Zemax License Manager from Start > Zemax Opticstudio (Or OpticsBuilder, or OpticsViewer) >Zemax License Manager. Open the "License Information" or "View License" tab so see if it finds the network license automatically. 

    If you do see a license, move to Selecting and using the network license

    If you do not see any licenses, move to What to do if the license is not found automatically.

What to do if the license is not found automatically


If the key was not found automatically by the client machine, follow the configuration steps below to help specify the network server where the license is hosted. 


1. Obtain the Zemax license server's machine name. Note that Zemax support does not know your server name as we do not host your license. It is typically hosted on a server in your orgnaization's network. 

Options to find the server name:

  • Check with a colleague that is using the same license. You can get the server name from their  Zemax License Manager application. It will be listed in the "Location" column next to "hosted on". See the example picture:

  • If this is at a business, log in to your Zemax account profile page. Open the license number you want access to and the License Administrator will be listed. Email the administrator and request the Zemax Licence server name.

  • If this is at an educational institution for an optics class, check with the class instructor.

2. Enter the server name into your settings. To do so, open the Zemax License Manager application and select Launch Sentinel Admin Control Center (ACC). This is located in the Troubleshoot tab (ZLM V2) or at the top of the Zemax License Manager (Classic) or. 

Tip: If the Sentinel admin control center web page gives an error message when opening, see "Repairing the license runtime" section of "How to troubleshoot softkey license issues."

3. As pictured below, open Configuration > Access to Remote License Managers. Make sure Allow access to Remote Licenses is checked. We recommend you also select Aggressive Search for Remote Licenses if it an option. Newer releases do not show this option. 

4. In the Remote License Search Parameters box, input the machine name of the network license server you would like to access.

We recommend using either the raw machine name such as servername, or the fully qualified name such as if you know it. Do NOT include http:// or any port number 1947 in the machine name.  

Also do not use any version of "Servername" as this is just an example. 


5. Click Submit when done entering the server information. 

6. Check under Options...Products on the left to see if the network license has become visible.  If you see a license for a Zemax product (it will have a vendor number 114811) , close the Admin Control Center and move to Selecting and using the network license.


If the license key is still not found after entering the server information, try these options:

  • Make sure you are connected to the company network directly or via VPN. 
  • Restart the machine. That will ensure the licensing service has saved and refreshed the network settings.
  • If you are logging in to a company network via a VPN connection, your IT department may need to configure the VPN server to pass through traffic to the license server's IP address (Port 1947). Zemax cannot help you configure your company firewalls.
  • We also recommend verifying that your security software is not blocking access to the license software. Check your security software's logs to see if either the HASP_RT.EXE in the OpticStudio installation folder, or HASPLMS.exe in C:\windows\system32 has been blocked. Instructions for Mcafee Enterprise is covered in the Frequently Asked Questions section at the bottom of this page.

If you still cannot get Opticstudio to locate the license, feel free to contact Zemax support or your license administrator or company IT department for further help. 


Selecting and using the license

  1. Find the network license you wish to use and select Default or Set as Default. Some Zemax licenses require a login to use. If this is the case, a screen will pop up requesting your Zemax account email address and password. Login with your Zemax account email address and password.

    Tip: If it says you are "not authorized" when logging in to the license. To solve this, log in to your Zemax account profile page. Click the license number you want access to see the License Administrator. Email the administrator and request they add you as as a license End User.

  2. Once the license default is selected you will be returned to the View License page. The Default button will be blue, indicating which license is your default.

  3. Restart the application to use the license and you are done! You must remain connected to the network to use the license. If you want to use the license offline, see the next section - Zemax License Manager (Version 2) license check out

    Tip: If your client machine gets a "key not found" error even if the license is displayed or other errors, there is additional troubleshooting in Resolving network license issues on client machines 




Zemax License Manager license check out

Using the Check out feature is optional. Zemax software will automatically use a network license seat when it launches and release the license seat back to the server when it closes. Most users will just make the license "Default' and use it while connected to the network.

If you need to leave the network you can check a seat out before you go offline. This dedicates a license seat to your machine for 1 or more days (14 days is the default server setting), so it's not recommended to use this feature unless you really need it. 

If you do use check out, we recommend checking it back in as soon as you no longer need it rather than letting it expire. This will maximize the availability of license seats for others.

To check out a license seat for offline use, follow these steps:


  1. Close OpticStudio to ensure the license seat is not in use. 

  2. Launch the Zemax License Manager (ZLM). For OpticStudio licenses, you can find the Zemax License Manager in Start...All Programs...Zemax OpticStudio.

  3. Open the "View License" tab. Look for your network license - it will have "Network" in the product description. Make sure there is at least 1 Available seat or you will have to wait until another person stops using the license to check one out. 

  4. Click Check Out

    TIP: If you receive any check out errors, see the article Resolving network license issues on client machines 



  1. If the check out was successful, an additional entry in the ZLM will appear with the following information. It will also be made your default license. The date by "Checked Out Until" is the date and time the license seat will expire and automatically stop working. The length of time is set by your network server administrator. 



  1. Once the license seat is checked out, the client machine may be disconnected from the network. Press OK, and you are done!

  2. To return a license seat before it expires, simply press Check In.

    Note that your computer needs to be online and be able to see the same license number you checked out in the Zemax License Manager. 




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 



If you get a "key not found" error even if the license is displayed or get errors checking out a license seat, see Resolving network license issues on client machines 


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