If you previously had a legal copy of Windows 10 on your computer but reinstalled it, you don't need a key.
If you have an old laptop or a retail box for Windows 7, 8, or 8.1, you can often use that 25-character key to activate Windows 10. : Press Windows Key + I . Update & Security : Select Activation . Change Product Key : Enter your old Windows 7 or 8.1 key. how-to-activate-windows-10-for-free-in-a-legal-way-aug-2022
: If the key is valid and hasn't been used on too many devices, Windows 10 will activate and grant you a digital license. 2. Digital License Linking (Reactivation) If you previously had a legal copy of
: During setup, sign in with the same Microsoft Account used previously. Update & Security : Select Activation
Within the tech community, the hosted on GitHub (often associated with the "massgrave" site) is the most popular method.