RAD Server License for RAD Studio Enterprise

I've been buying the Maintenance Support each year for RAD Studio Enterprise since my original purchase of RAD Studio XE8 Enterprise. My question is this: How do I get and use the 10 User License for RAD Server? Do I just register it using my RAD Studio XE8 Enterprise Serial Number or do I need a RAD Server license/serial number in order to use it?

Thanks in advance,

Kelly.