If you already have a legitimate volume license key (often used in corporate environments) and need to apply it to a machine without using the GUI, you can use the and command-line scripts.
The key follows a specific structure: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX . office 365 key
I need my Office 365 apps downloaded. It wants my Product Key. If you already have a legitimate volume license
This requires a valid Volume License Key and the Office Deployment Tool installed on your machine. office 365 key
Both options bind the subscription directly to a Microsoft account upon redemption.