Hello,
I would suggest you to have a Look at these Articles:
About renewing your Symantec Endpoint Protection Small Business Edition license
http://www.symantec.com/docs/HOWTO54775
Activating your new or renewed Symantec Endpoint Protection 12.1 product license
http://www.symantec.com/docs/HOWTO55294
Recovering a deleted license
http://www.symantec.com/docs/HOWTO54924
Also check this -
Symantec™ Endpoint Protection Small Business Edition 12.1.2 Installation and Administration Guide
http://www.symantec.com/docs/DOC6151
Hope that helps!!