You’ll get an EA App CD Key for FIFA 21 that needs to be activated on the EA Client. Log in and activate the key there, making it ready for download. You can do that by clicking on “Redeem Product Code” and enter the code there, and the game will be added to your games list. If you don’t have the EA Client yet, you can download it here.
A FIFA 21 key for the EA-Client does not expire and after activation FIFA 21 can be downloaded and played forever.