Hello,
Every product has a different license file and every license file works either on computer basis or user basis.
Symantec Endpoint Protection 12.1 license works per computer machine basis.
However, you could try to contact Symantec Licensing Department for the same.
Phone number: 1-800-721-3934
Email: license@symantec.com
Contact Us
http://www.symantec.com/partners/support/contact-us.jsp
Assistant & Information
http://www.symantec.com/support/assistance_information.jsp
Once, you have the latest SEP 12.1 License, you could also try inserting the license number and try registering them again..
Importing a license
http://www.symantec.com/docs/HOWTO55080
Activating your new or renewed Symantec Endpoint Protection 12.1 product license
http://www.symantec.com/docs/HOWTO55294
SEP 12.1 and License Concept
https://www-secure.symantec.com/connect/articles/sep-121-and-license-concept
Hope that helps!!