As part of my MSDN subscription, I installed SQL Server 2012 SP1. Today, when try to connect to the database, I saw it didn't work. When trying to go in SSMS, I get the message:

Evaluation period has expired.

I do not understand why this installation would expire. As part of MSDN, this is installed on my PC for development and should be ok to run as is without expiring. Can someone explain me why I am ending up in that situation?