“This code has already been redeemed” Microsoft Error Message
This is what to do if you see a “This code has already been redeemed” error message on the Microsoft redemption page.
Check your services & subscriptions page
Sometimes the Microsoft redemption page glitches during redemption and states the key has already been redeemed, when it’s actually been applied to your account already.
Check the services & subscriptions page of your Microsoft account to see if the software is already linked to your account on the following page: https://account.microsoft.com/services