You get a message saying the following:
Your MATLAB license will expire in ## days.
Please contact your system administrator or MathWorks to renew this license.
MATLAB is currently site licensed by Campus Office of Software Licensing (COSL) at UCSB.
They have the following instructions with regards to licensing here:
The instructions have specific directions based on if it is installed on Windows or Mac OS X.
If you are still having issues with regards to activation, you should contact firstname.lastname@example.org for further assistance.