if you are using ZD1112 then you need to buy following lic:
909-1125-ZD00 -->
ZoneDirector 1100 License
Upgrade from supporting 12 to supporting 25 ZoneFlex Access Points
-- Quantity 1
if you are using ZD1205 model then you need to buy following lic:
909-0001-ZD12
--> ZoneDirector 1200 Single AP
License Upgrade SKU. Max orderable upgrade license quantity is 70.
quantity 13