can i use my windows license i used in bootcamp again?

Hey,
I have installed windows 7 in bootcamp.
and i boucht upgrade license for windows 8.
so i now have windows 8 in bootcamp.
but can i use the windows 7 licens again in parallels desktop?
it is a oem licens but i think this isn't a problem because it is the same mac.
can somewane help me?

 

If you bought a Windows 8 upgrade license, legally the Windows 7 license is tied to Windows 8 upgrade license, it's like they are part of the same license.