Start-->All Programs-->Microsoft SQL Server 2008-->Configuration Tools-->SQL Server Installation Center
-->Maintenance-->Version upgrade, then follow the prompts and click Next until the product key is entered
Development version: PTTFM-X467G-P7RH2-3Q6CG-4DMYB
Enterprise Edition: JD8Y6-HQG69-P9H84-XDTPG-34MBB
If the evaluation period has expired after the above operations, modify the registry:
Change the "CommonFiles" value in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\100\ConfigurationState to 3, and perform the above operation again.
The solution for sql server 2008 installation that needs to be restarted all the time:
Start --> Run --> regedit
Locate the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager location
Then right-click PendingFileRenameOperations in the right window, select Delete, and then confirm