Windows 2008 R2 Standard > Enterprise in-place upgrade

Today I needed to upgrade a Windows 2008 R2 Standard OS (with a valid MAK key) to Enterprise. The reason was to utilize more RAM (>32 GB) on the server.
This is how I complete the upgrade:

1. Did a backup of the server
2. dism /online /set-edition:ServerEnterprise /ProductKey:489J6-VHDMP-X63PK-3K798-CPX3Y
   (this is a KMS key from Microsoft, LINK) from Jamie’s blog
   Got message “The operation completed successfully”
3. Reboot server
4. Logon to the server
5. Enter a valid MAK key
6. Reboot server
7. Now I had an error that RDP wasn’t working (and Remote Desktop disappeared from Remote tab)
8. slmgr /rearm (To remove the current license)
   Got message back that the command completed successfully and that I needed to restart
9. Reboot server
10. slmgr /ipk VALID-MAK-KEY
    Got message back that the key installed successfully
11. slmgr /ato
    Got message back that the product was activated successfully
12. Reboot server

The server then was upgraded to Enterprise OS with working RDP. I did this on a server with 4 SQL instances without any additional errors.