i would ask a question like this here:
http://community.arubanetworks.com/t5/Unified-Wired-Wireless-Access/bd-p/unified-wired-wireless-access
it depends a bit where you want to go for. in this case a master with a local sounds like a possible deployement. this is often on different layer 3 networks and you can use centralized licensing fine then and have APs terminate on either the master or the local. with fallback if either fails.
the only thing is that if your master fails configuration changes are not possible. also you need to replace the licensing server with 30 days. so if you are fine with that and can make that happen in normal time (make backups, have support on hardware, test the replacement plan) then you should be fine.