If you perform a clean install on the first attempt, you will have to start over from an activated Windows 7 or Windows 8.x installation.By default, Windows 10 builds are pre-keyed, meaning, you do not have to enter a product key and should not be prompted to enter one, as long as you upgraded from an activated Windows 7 or Windows 8 or Windows 8.1 license or Windows 10 Preview build.Windows 10 uses its own unique product key. A Windows 7 or Windows 8/8.1 product key cannot activate Windows 10.Understand and Fix Windows 10 Product Key Activation How to Find Your Product Key After Upgrading to Windows 10.How to Find Your Windows 10 Product Key.For more on activation issues, take a look at these articles: Update: This was written for issues when Windows 10 was initially released in 2015. Regardless of this, product activation remains a part of Windows 10. In this article, we take a look at product activation and troubleshooting steps. The most notable being that Windows 10 is free for existing Windows 7, 8/8.1 users for the first year.
