WINDOWS 10 PROFESSIONAL PRO 32/64 BIT STICKER COA license key label for computer How to find Windows 10 product key: You don’t always need a product key to clean install Windows 10 Since Microsoft has your computer’s ‘digital signature’ from the initial upgrade it recognises the combination of components when you do a clean install and automatically activates Windows. This means you can safely skip the screen which asks for a product key at the start of the installation