a customer has ZD1100 with 6 APs and 6 licenses all used up. they want to add one more AP and 1 license. we provided 901-R310-WW02 and 909-1112-ZD00. it appears that this ZD 1100 license upgrade is expensive supporting 6-12 APs. is there a single license upgrade that is not too expensive or alternative BOM for my customer?