

However, there are exceptions, as described in this Microsoft support document (Opens in a new window).

Windows 10 typically does not require a product key. Okay, so let's first go through the scenarios in which you would or would not need a product key to reinstall and reactivate certain Microsoft software. What if you need the key for Windows or Office? You can use a third-party utility to display the keys on your PC before a crash occurs, save those key numbers, and then have them squirreled away just in case. But with older versions of Windows and with Microsoft Office, a product key is required. With Windows 10, the OS should automatically activate as the license is usually digital and doesn't require a product key. How can you do this without the product keys for your software? There are some tricks, but you'll have to use them while your current hard drive is still alive and well. You just replaced your PC's hard drive, but now you have to reinstall and reactivate Windows or Office on your new system.
