Windows Server 2012 does not offer a Change Product Key link that is commonly found in Windows Server 2008. To change the product key in Windows Server 2012:
1. Open the Start Menu.
2. Type in Slui.exe 0x3 in the search box.
3. Click the Slui.exe 0x3 icon.
4. Type in the new product key in the Windows Activation window and click Activate.