In 2000 and 2003, as long as I remember, when you purchase the Terminal Service CAL license, you receive the CAL key. That's what I expected but the license for 2008 and 2008R2 is different.
The CAL key will not be provided until you contact Microsoft during the License server configuration.
1. On the Server Manager, click "Add roll" and select "Remote Desktop Services"
2. Select Remote Desktop Licensing
3. If you want to install the license for a forest or a workgroup, check Configure a discovery scope... and select a desirable choice. Otherwise accept the default (Domain).
4. When the Remote Desktop Licensing roll was installed, open RD Licensing Manger from Administrative menu --> Remote Desktop
5. Expand All servers and right-click on the license server
6. Select Active Server. Activate Server Wizard will start.
7. Select Telephone from the Connection method drop down menu.
8. Select the country.
9. Make sure you have the authorization number and license agreement number for the CAL handy. Call the given phone number. The support technician will issue the CAL key and walk you through the rest of the process.
You can run Terminal /RD License service for 120 days without installing a purchased CAL key.