Is it obligatory to pay a debt owed to an online platform as a result of advertisements, and how can payment be made if the bank card is no longer in use?

The debt owed to the entity must be repaid as long as the entity has not waived it, just like any other obligatory right. Otherwise, Allah will be the adversary of the debtor on the Day of Judgment, as stated in the Hadith Qudsi: "There are three whose adversary I am on the Day of Judgment: a man who gave a promise in My Name and then broke it; a man who sold a free person [as a slave] and consumed his price; and a man who hired a laborer, benefited fully from his labor, but did not give him his wages." The repayment can be made by any method that ensures the right reaches its owner, whether by reusing the bank card or by transferring the amount.