From Manual:
"Server is Unreachable:
If a licensing client does not receive 3 consecutive heartbeats from the server, it assumes that the server is down,
and that any APs directly associated to the server are also down or have failed over to another controller. The client
then adds any licenses used by the licensing server into to the pool of available licenses on that client. When a
license client is unable to reach a license server for 30 consecutive days, it removes any shared licenses pushed to
it from the licensing server, and reverts to its installed licenses. If the 30-day window has passed and yet controller
does not have enough installed licenses for all its associated APs, the controller will nonetheless continue to support
each AP. However, when an AP reboots and its controller does not have enough licenses, that AP will not come up."
best Regards