How to upgrade from windows 7 home to windows 7 professional

[Moosemuffins]

Hello,
I had Windows 7 proessional on my system ad had some issues(not with win7pro) and the big computer store in town had to wipe and reinstall. But what they installed was win7home. My question is how can I upgrade to pro without buying it(have license)?

 

[The Stealthinator]

If you have a laptop or desktop that you bought and you don't have an OEM disk, you'll need to request one from your company. If the machine was one you put together yourself, then just use the same CD you did earlier to install windows.