After payment you will receive a unique code that must be communicated to the seller through personal correspondence.
Also, after payment, you need to provide the username / password from your xbox live account to the seller.
If it is not possible to activate the subscription to your account, you will need to create a new account, which can then be made "home" and freely play on your personal account in the games downloaded by subscription.

Your personal account must not have a valid EA ACCESS subscription

Play unlimited with EA Access! Enjoy tons of fun games, exclusive trials and attractive discounts.
ВЂ Play whenever you want and as much as you want in any games from the huge collection of EA, which includes blockbusters from such series as Battlefield, FIFA, Need for Speed, and many others! The selection of games is constantly updated, so you will always find something interesting for yourself.
• Play First exclusive trials allow you to play new EA games days before the official release. Your current level is saved and carried over to the full version if you purchase it. In addition, trial versions are valid for a long time after release, so you can evaluate the game at any time.
• You automatically save 10% on EA digital merchandise on Xbox One, including full games, DLC, Ultimate Team content, and more. Looking for new DLC to play from the collection? Or purchase the full game after using the Play First trial? No problem. Ready to check out EA´s awesome collection of games? Register now. You can unsubscribe at any time.