If you purchased from Microsoft, check your email for a purchase confirmation message. In many cases, product keys purchased elsewhere won’t work correctly. While there are other sellers online that claim to sell digital licenses, the only authorized Windows 10 retailers are Microsoft and Amazon. If you purchased Windows 10 online as a digital download or physical media, your license key may still be stored on the retailer’s site. Recover Windows Product Keys Using Purchase Details There are multiple ways to recover a Windows 10 product key, depending on your situation, as you’ll see below. Have you ever tried reinstalling Windows software but had no idea what the license keys and serial numbers were? Sure, they were probably on the packaging or in an email, but they might be gone now.