There is no licensing needed for doing the upgrade. All you need to do is download the 2.0/2.5 upgrade files from CCO:
http://www.cisco.com/cgi-bin/tablebuild.pl/wlan-sol-eng and follow the respective readme files for doing the upgrade.
Note: You cannot directly upgrade from 1.3 to 2.5. In your case, the upgrade path would be from 1.3->2.0 and then from 2.0->2.5