Convert Windows Server 2012 Evaluation to the Full Retail Version
For those who decided to test the Evaluation Version of Windows Server 2012 and now want to use it for production, Microsoft published Evaluation Versions and Upgrade Options for Windows Server 2012 TechNet article to help you move from one edition to the other. It also shows the available upgrade paths to Windows Server 2012 and a per-server role considerations table that should be followed before upgrading.