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Using Environment Variables to Point to a NI-VLM or FlexLM Server

Updated Apr 25, 2023

Reported In


  • NI License Manager


FlexLM, FlexNET

Issue Details

I know I can configure my client computer to point to a volume license server from NI License Manager (NILM) by going to Options»Preferences and entering the server name in the Use Network License Servers field. Is there another way to configure my client to select or choose a volume license server?


To view or edit environment variables in Windows, 
  1. Go to Start»Settings»Control Panel»System»Advanced
  2. Click on the Environment Variables button. The format of the environment variables is: PORT_NUMBER@SERVER_NAME where the PORT_NUMBER is optional. 
  3. If the port number is not present, it is assumed to be 27000. If you add an additional server/port number, separate each server/port with a semicolon.

Additional Information

When License Manager or any NI application software is launched, it checks the following locations that identify volume license servers in the order listed:
  • NILM_LICENSE_FILE Windows environment variable
  • LM_LICENSE_FILE Windows environment variable
  • Servers configured in NI License Manager in the Options»Preferences»Use Network License Servers field
These locations contain the names and port numbers of FLEXnet license servers which FLEXnet licensed application software checks for permission to launch.  The NILM_LICENSE_FILE Windows environment variable is only used by NI software. The LM_LICENSE_FILE environment variable is not specific to NI; thus, FLEXnet license servers used by other non-NI software programs may appear in this variable as well. Neither of these environment variables are required for NI licensing to work. They are available as an advanced option for those license administrators accustomed to managing licenses with FLEXnet software using environment variables.

Servers configured in NI License Manager in the Options»Preferences»Use Network License Servers field are only used by NI software and are not used by non-NI software that uses FLEXnet.

Note that if you have many servers configured, it may take longer than normal for your client software to launch. The client software will check each of the servers referenced in the order that the environment variables and NILM server configuration is listed above. If you want to reduce your software launch times, consider doing the following:
  • Removing unnecessary servers from NILM_LICENSE_FILE or LM_LICENSE_FILE.
  • Use the above environment variables to point to the most common license servers first.
If you have any NI software that uses local activation, they would still try to retrieve the licenses from the servers specified. If you need to use LM_LICENSE_FILE for other software that require licenses, you could experience long launching time of your NI software. The workaround is to use vendor specific vendor variables, such as VENDOR_LICENSE_FILE, instead of LM_LICENSE_FILE.