What is the ruling on purchasing for a relative using an interest-bearing credit card, knowing that there is no necessity for the purchase, and is it permissible to benefit from programs purchased in this manner?

Credit cards that involve a usurious condition are impermissible to issue or use, even if the cardholder intends not to delay payment. It is also impermissible for someone else to use them. However, as for programs or other items purchased with such a card, there is no harm in benefiting from them.