A Forza Horizon 3 license key, also known as a product key, is a unique 25-character code that serves as a digital signature, verifying that you have purchased a legitimate copy of the game. This key is required to activate the game on your Xbox console or Windows PC, allowing you to access the full range of features and gameplay. The license key is usually provided with your game purchase, either in a physical box or via email, depending on the retailer.