It is possible to apply more licenses than the controllers support. In older versions, the Remote APs (RAPs) were able to connect at a ratio of 4:1 on some controllers. However, that is no longer the case.
After the upgrade to 6.3, centralized licensing will ONLY pool the licenses that are NOT embedded on the controller. So, if an AP terminates to a controller with embedded as well as additional license keys, that AP will use the embedded license FIRST.
If you are looking at anything relating to license tranfers, etc, please consult with your Aruba sales rep.