In this article we explain how to deal with the error code "This product key has already been used". This means that the product key has already been activated and you need to log in to your account to install the product from there.
This guide is exclusively for Microsoft Office 2021 Home & Business (MAC) users. If you have purchased a different version of Office and encounter a similar error code, please click on the "Report Key" button located at the bottom to submit a report.
STEP 1
Login into your account here: https://account.microsoft.com/services
STEP 2
You should now see your activated Office under "Services & Subscriptions".
If you don't see it on your account, please report your key by clicking the button below.