CCA is licensed in two manners:
The CAM is licensed on the basis of how many CASs it can manage.
1 CAS Failover Bundle = 1 Server Count
CAM comes in 3 Flavors: Lite(manages up to 3 Servers), Standard(manages up to 20 Servers), & Super(manages up to 40 Servers)
The CAS is licensed on the basis of how many users are logged in. The easiest way to understand this is to think about how many Online Users show up int the IB/OOB OU List. The only caveat to this is that if you are using Device Filters that are marked as "Check" you need to include them in the CAS User Count.
CAS comes in many flavors ranging from 100 users to 2500 users