Activate Windows Server Core 2008 R2

1. Logon into the server console.
2. Install your MAK key using command:
    slmgr -ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
Where XXXXX-XXXXX-XXXXX-XXXXX-XXXXX is your 5x5 MAK key supplied by Microsoft.
3. To activate Windows Server 2008 Core write the command:
    slmgr -ato
4. Display the current license information of Windows with activation status and last 5 characters of partial product key:
    slmgr -dli