Finding your Windows product key depends on how you obtained your copy of Windows. If Windows came pre-installed on your PC, the product key is usually on a sticker on your device or included in the packaging. If you purchased Windows digitally, the key would be in the confirmation email you received. If you can't find your key, you can use Command Prompt or PowerShell. Note that this method might not work for all versions of Windows, and in such cases, contacting the retailer or Microsoft Support may be necessary.