Once you install evaluation edition of SQL Server 2008 and then perform in place upgrade to full version, you may get below error message when you open SQL Server Management Studio.
For better search, below is the text of the message
Microsoft SQL Server Management Studio:
Evaluation period has expired. For information on how to upgrade your evaluation software please go to http://www.microsoft.com/sql/howtobuy
Have a close look at error… This is for Management Studio. This means that this is the problem with management studio only. If its not yet expired, inside of Management Studio, going to Help > About... still shows this the expiration countdown.
This is identified as a known issue where SSMS is not upgraded when you do edition upgrade for SQL Server 2008. To workaround the problem you can hack registry keys. Set CommonFiles registry value to 3 in HKLM\SOFTWARE\\Microsoft\Microsoft SQL Server\100\ConfigurationState Registry Hive. You will then need to reinstall (if the tools are not installed currently) or run edition Upgrade. Reference: connect bug
This is already fixed in SP1.
Update: 12 May 2009.
KB article published for same issue. http://support.microsoft.com/kb/971268