you can use one only for one account

Sea of Thieves required.
Valid only for the Xbox Series X|S and Xbox One console versions of the game.

Limited to one per account.

Product activation:
1. Sign in to your account or create a new one
2. Follow this link https://redeem.microsoft.com/ and activate the key for your account
3. Accept the terms of the agreement and enter the received key
4. Follow the instructions to install the game