If your purchase of Office or Microsoft 365 came with a product key, you enter your product key on one of the websites listed below for your product. After you enter your key, you can download and install Office, or you can renew your Microsoft 365 subscription.
Example of an Office or Microsoft 365 product key:
To redeem a new purchase
Step 2: Sign in with your Microsoft account, or create one if you don’t have one. Be sure to remember this account so that you can install or reinstall Office later, without a product key.
Important: If you’re renewing your Microsoft 365 subscription, enter the Microsoft account that’s associated with your subscription. I can’t remember my Microsoft account.
Step 3: Enter your product key, without hyphens, if prompted. If you don’t see the option to enter your product key, it was entered for you automatically.
Step 4: Follow the prompts to finish the redemption process.
To install or reinstall Office
If you see the error This product key has already been used when you enter your product key on www.office.com/setup or Microsoft365.com/setup, this means your product key has already been redeemed and is no longer needed.
Instead, use your Microsoft account to sign in to account.microsoft.com and install your Office product.
Note: If you’re trying to allow up to 5 other people to install Office using your Microsoft 365 Family subscription, see How to share your Office 365 Home subscription benefit.https://www.microsoft.com/en-us/videoplayer/embed/RE3tnnz?pid=ocpVideo0-innerdiv-oneplayer&jsapi=true&postJsllMsg=true&maskLevel=20&market=en-us