You can check who is using a network license in the license server dashboard.
To check who is currently using a network license, use any web browser to access this page: http://YourServerNAMEorIPaddress:2468/web > Usage tab.
Furthermore, you can enable usage logging to a CSV file in the license server.
To enable this feature:
1. Edit this config file with notepad in your license server: "C:\Program Files (x86)\AGA-CAD Network Licence Server\Services\Slps.Distributor.Services.dll.config"
2. Add this string: <add key="Slps.Distributor.Service.EnableUsageLogging" value="true"/> in <appSettings> and save the file.
3. Then go to services.
4. Locate and restart Slp.Distributor.Host service.
5. Next time when someone uses the network license, it will be logged in here: C:\Program Files (x86)\AGA-CAD Network Licence Server\Services\Usage
License release is accomplished by going to the Dock License Manager (gear icon at the bottom right) > Manage under network license> Release Network Licenses.
Also, the license is released when Revit is closed.