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I bought Windows 8 Professional, updated to it from my Win 7 Pro and it's great. All in all, I wanna keep using Windows 8, but something went wrong with my Visual Studio 2012 Professional installation. Now there is no way I can install the target version for .NET 4.0, and I really need this to comply with old projects without affecting other developers.

I do have an official license key, bought when installing Windows 8, so my question is, now that I need to format, then reinstall Win 7 Pro, then reupgrade to Win 8 Pro, how do I make sure my next activation is successful?

In other words, how can I not change, but remove my license so I can use it again when everything is fresh and updated?

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up vote 4 down vote accepted

If you want to use your license on a clean install, you need to backup and restore your activation files.

  • Backup the store folder located here: %WinDir%\System32\spp\store\.
    • Make sure that your backup folder contains the three files: data.dat, tokens.dat, and cache\cache.dat.
  • To uninstall a key, right click on the Start corner > Command Prompt (Admin) > Yes > Type:

    slmgr -upk
    • Actually, there is no need to uninstall your key before clean install. You can just skip this step. After you format, your Windows 8 installation will be removed anyway.
    • However, in the clean installation, if you had used a default install key, you should uninstall that key.
  • After you clean install Windows 8, boot into safe mode > Right click on the Start corner > Command Prompt (Admin) > Yes > Type:

    net stop sppsvc
  • Restore the backed up store folder to its location in %WinDir%\System32\spp\.

  • Restart.

It is a good idea to make a backup of your OS drive before performing these steps and a clean install.

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No, you can download the ISO file for Win8 PRO and re-install Windows 8 booting from that ISO (dvd or usb) using the serial given during the update process.

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ok, but this does not answer my original question: How to uninstall the license. – balexandre Nov 6 '12 at 9:38
you can't. Windows activate that serial on your pc and vinculate it on the hardware you're using – AndreaCi Nov 6 '12 at 11:10
@balexandre - You wipe the hdd. This would "uninstall" the license and allow you to use the Windows 7 license. – Ramhound Nov 6 '12 at 12:03

You cannot uninstall a license key in a way you uninstall an application.

If you use the key only on one computer, Windows will activate.

That means you can reformat the drive, install Windows 7 Pro with its key, upgrade to Windows 8 with its key.

You can even transfer the upgrade to another computer, if it's eligible for upgrade provided you re-install Windows 7 on your current which was upgraded.

If you have a retail version of Windows 7, non-OEM, you can install it on another computer, and it will activate, although you may have to use phone-activation (since the hardware changed significantly). Then you can also upgrade it to Windows 8. Of course, this assumes you still use it only one computer.

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I have used one license key on many computers and it never got mad at me :P. As long as 200 people don't use your key I think OP should be ok... – Wijagels Nov 6 '12 at 13:22
@Wijagels You were lucky! ;) I had to re-activate my Windows 7 installation after I had changed motherboard. And the phone robot asked me on how many computers I installed this copy of Windows. – Alexey Ivanov Nov 6 '12 at 14:09

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