Cisco Unified Wireless Network Software Release 4.0 enforces software-based licensing. Customers are prompted to enter license certificates by all new Cisco WCS SKU families (except the Cisco WCS Demonstration License). Existing customers migrating to Release 4.0 will also be affected by licensing. Cisco WCS licensing enforcement is tied to the following parameters:
Host name-The host name of the Cisco WCS server is now required during the registration process. Licenses issued are tied to the original host name designated during the registration process. (To change a host name, read Changing PAK Certificate Host Name.)
Feature option-The Cisco WCS feature option purchased, Base or Location, is now tracked by the Cisco WCS licensing system.
Access points-The number of access points supported in set increments of 50, 100, 500, 1000, or 2500 is now tracked by the Cisco WCS licensing system.
Demonstration license-This free, location-enabled Cisco WCS demonstration license supports 10 access points for up to 30 days.
Selecting the Correct Cisco WCS SKU
Each new Cisco WCS SKU family, except for the Cisco WCS Demonstration License, provides licenses for 50, 100, 500, 1000, or 2500 lightweight access points.
From this good WCS Licensing doc;
Cisco Wireless Control System (WCS) Licensing and Ordering Guide
The WLC is hardware based and ordered as such,for example, if you are rolling out 10 lightweight access points in your campus environment today but know you will deploy an additional 10 lightweight access points within the next year, it is recommended that you deploy a wireless LAN controller that supports 25 access points (Cisco 4402-25) rather than a controller that supports only 12 access points (Cisco 4402-12).**There is no further Licensing involved for the WLC.
For the WLC 4400 Number of Lightweight Access Points Supported 12, 25, 50, or 100
Here is an excellent doc;
Guidelines and Tools for Migrating to the Cisco Unified Wireless Network