Is it permissible for a group to offer a service of purchasing goods with repayment within a month without interest, in exchange for an annual subscription?

The third case is usury (riba). The second case: If the interest is undefined and increases with delayed payment, then it is the prohibited usury of Jahiliyyah (pre-Islamic era). However, if there is a predetermined increase in price that does not exceed what was agreed upon in the contract, then this is permissible. The first case has no objection, provided that there is no agreement on interest for delayed payment, and that the entity does not deal in usury. It is advisable to avoid that which is disputed in its permissibility, as a precaution for one's religion.