If you are installing on a PC that previously had Windows 8.1, it will auto-activate upon connecting to the internet. No need to re-enter the key.

Q: Can I still download Windows 8.1 Pro from Microsoft? A: Yes, you can still download Windows 8.1 Pro from Microsoft, but you may need to search for the product page and follow the steps outlined in this article.

Microsoft hosts the Windows 8.1 ISO files on their official "Software Download" page. Following these steps ensures you get a secure, malware-free version of the operating system.

Several "untouched" official ISOs originally from Microsoft have been mirrored here for preservation. Windows 8.1 Home and Pro (x86/x64) Windows 8.1 Professional Original ISOs with Update 3 Key Technical Notes Activation:

There are several reasons why you might want to download the Windows 8.1 Pro disc image: