Is it permissible to sell free trial subscriptions for an Xbox device for a small fee, and is it permissible to enter a fake credit card to obtain these subscriptions?

There is no objection to playing electronic games that are free from harm and Shariah prohibitions. It is permissible to benefit from the available trial month, but it is not permissible to resort to deception to extend the period or re-subscribe using multiple names if the company prohibits it, due to the Almighty's saying: ﴿O you who have believed, fulfill [all] contracts﴾ (Quran 5:1), and ﴿And fulfill [every] commitment. Indeed, the commitment will be questioned﴾ (Quran 17:34), and the Prophet's ﷺ saying: "Muslims are bound by their conditions." This deception falls under cheating, fraud, and consuming wealth unjustly.

Selling the trial subscription is permissible as long as it is not a deception to renew the subscription or subscribe with multiple names. It is not permissible to use a forged card to obtain the subscription, due to its violation of fulfilling the contract.