Reinstalling and reactivation

Hi there. I have a Windows 7 pro machine where I am dual booting with Windows 8 pro on a VHD. Windows 8 Pro activated too fast, without my noticing. Now I am considering deleting the VHD and simply upgrading the Windows 7 partition. Will Microsoft cause problems because I am activating again? Or how would Microsoft know that I removed Win 8 on the VHD? Thanks in advance for your help or comments.