As part of Windows 10â€™s first November update in 2015, Microsoft changed the Windows 10 installer disc to also accept Windows 7 or 8.1 keys. This allowed users to perform a clean install Windows 10 and enter a valid Windows 7, 8, or 8.1 key during installation. Windows 10 would then report that key to Microsoftâ€™s servers, and Windows 10â€™s activation servers would give your PC a â€œdigital entitlementâ€ (now a â€œdigital licenseâ€) to continue using Windows 10 for free, just as if you had upgraded.
Now, even though the free upgrade offer is technically over, thisÂ method still functions in every version of Windows 10, from 2016â€™sÂ Anniversary UpdateÂ to theÂ November 2019 Update. It works when installing Windows 10 withÂ installation mediaÂ or by entering the key after installing Windows 10. Enter any Windows 7, 8, or 8.1 key that hasnâ€™t previously been used to upgrade to 10, and Microsoftâ€™s servers will give your PCâ€™s hardware a new digital license that will allow you to continueÂ using Windows 10 indefinitely on that PC.