possible to install windows 7 pro without 7 home key?

Please forgive me, but I know little about computers. Hopefully this fact will be changing shortly.

I've purchased a gaming computer from a friend. He wiped the computer clean before he shipped it and I need to install windows fresh on it. He had windows 7 pro on the computer, which he upgraded from home. He no longer has his key for the home version, but has the key for the pro upgrade.

Is it possible to legally and ethically reinstall that upgrade to pro on the computer without having to purchase a new install of windows 7 home? Another friend who works in IT is helping me build and set up the computer, but he isn't sure if this is possible. Any help is appreciated, and I apologize for my lack of knowledge on the subject.

Keith

Welcome to the forum,

You should be able to do the install with one of these methods,

Clean Install with a Upgrade Windows 7 Version

Thanks. I forwarded your link to people that can translate it :).

Appreciate the help.

Is the Professional key an Anytime Upgrade key, which is how Win7 is upgraded to a higher version without reinstall? Windows Anytime Upgrade - How to - Windows 7 Forums

If so then you need the underlying Home Premium to unlock the features in Professional which is all an Anytime Upgrade key does. It's can't be used to Clean Install Windows 7.

However if it's a Win7 Upgrade retail Professional key then you can use the installer ISO for your version provided in Windows 7 USB-DVD Download Tool to burn to DVD or flash stick, then follow the steps to Clean Install Windows 7. If there is any OS on the drive the installer will see it to allow use of Upgrade version key during install, otherwise leave the key blank and afterwards do the quick registry edit in Option 3 of Clean Install with a Upgrade Windows 7 Version to activate Upgrade version on a clean hard drive.

Other tips here will assure you get and keep a perfect Clean Reinstall - Factory OEM Windows 7 and also apply to retail.