i believe (still getting up to speed on this) that you will be fine for 30 days without a license server. probably as long as you dont need to add new APs.
from the 6.3 user guide:
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.
a backup license server would help, but i dont believe you can make a local a license server.
from the 6.3 user guide:
- A single master controller is connected to one or more local controllers.
Only the master controller can be a license server. A local controller can only be license client, not a license server.
- A master and standby master are connected to one or more local controllers.
The master license server will reside on the master controller, and the standby license server will reside on the standby master controller. Local controllers can only be license clients, not license servers.