Hi,
Thank you for posting your query on Symantec community.
In your case SEPM will show 100 clients over-deployed status & will keep sending notifications to partner/admin to renew the licenses.
When the license goes out of compliance the Symantec Endpoint Protection product goes into enforcement mode. There are two types of enforcement
1) Hard Enforcement: Applies to SEP 12.1 Small Business Edition, it blocks all the updates from Liveupdate Server.
2) Soft Enforcement: Applies to SEP 12.1 Enterprise Edition, It does not block all the updates from Liveupdate Server.
Refer this guide also:
Licensing enforcement rules
http://www.symantec.com/docs/HOWTO80852