Hi,
Thank you for posting in Symantec community.
I would be glad to answer your query.
After the trialware license expires, you must activate a paid license to retain full product functionality. You do not have to uninstall the trial-licensed version to convert your Symantec Endpoint Protection installation to a fully licensed installation.
Refer the following article:
About the trialware license
http://www.symantec.com/docs/HOWTO55075