First of all, thanks a lot for your suggestion, your feedback is very important to us - we'll evaluate its viability for future releases.
The license handling process is fully automatic - the license is sent when needed and released to the "free & available" status when not in use - that happens shortly after closing the 3ds Max (within seconds) / scene with Forest objects (within minutes).
It shouldn't be necessary to close the 3ds max, if there's temporarily no license available. Once there'll be an available license, it should be borrowed automatically after a while - upon our internal test all seem to work correctly on 3ds max 2017 & latest releases of our plug-ins. Might be, you've not reached the "status checking interval" - I would suggest you to wait a little bit more (within minutes any "free" license should be recognized).
Let me add, that an option to exclude specific workstations from getting a license from the server is by changing them temporarily to "Stand-alone mode", using "Start Menu->Itoo Software->Forest Pack Pro->Change License Mode". This way is possible to define easily the workstations that will use the available licenses.