Activating Windows Server 2008 R2 Core Edition

In the command line, paste the next command:  slmgr.vbs -ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX

(Where XXXXX is your Key)

Activating your Key: slmgr.vbs -ato

Other options of slmgr.vbs: http://adf.ly/6C6SD