Redeeming your product key is a one-time process that adds your new Office product to your Microsoft account. When you're done, you'll use your Microsoft account, not your product key, to install and activate Office.
Note: If you have an existing Office 365 subscription and don't use recurring billing, you can redeem a new product key to renew your subscription.
To get started, remove your product key from your Office package, or gently scratch the silver foil on the back of your product key card. If you bought Office from the Microsoft Store, your product key is on your receipt.
4. Follow the prompts
The next steps can vary, so follow the on-screen prompts for your product below
Provide payment info to enable recurring billing (if prompted), or confirm your subscription
Review your details to confirm your Microsoft account and Office product
On a PC, select install options (like language and 32-bit or 64-bit)
On a PC or Mac, select Install again
Next steps for Office 365 subscribers
Set up Office and email on your mobile devices
You can install Office on your mobile phones and tablets as well.
Did you buy multiple product keys?
Repeat the redemption process for each key to extend your subscription for up to 5 years.