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If you are reinstalling your windows 8 then you can use the same old product key for it.You can check your purchase confirmation email. In that email you will get your product key.
If you purchased a retail, boxed copy of Windows 8 , you’ll find your product key included on a card in that box. You may need to dig the box out of your closet to find your product key. Look for a card with a picture of a key on it.
PCs that come with Windows 8 have an encrypted product key embedded in their UEFI firmware. When you reinstall the same version of Windows 8 on a PC that came with it, the product key will be automatically applied and activated. You won’t see any product key prompt — it will all happen automatically.This only applies if you’re installing the same copy of Windows
Hi there! My name is***** you still having problems with this? i have a couple of suggestions. First, if Windows 8 was the original operating system on your computer, there should be a sticker somewhere on the pc with the product key. Secondly, when you upgrade to Windows 10, there is an option to revert to your previous operating system for up to 30 days. If you still have Windows 10 installed, and haven't tried to install 8 over it, let me know and I will provide detailed instructions for reverting back to the original operating system.