Is it permissible to take $25 from the Payoneer website in exchange for inviting my brother to register, and to take a $25 gift when the card is charged with $100?

There is no objection to subscribing to a free prepaid card or one with a known fee, nor to benefiting from its gifts or commissions when attracting customers. As for the gift resulting from topping up the balance, if it is not stipulated in the contract, it is more prudent to abstain from it and give it to the poor. However, if it is stipulated in the contract, it is not permissible to take it or enter into the contract that includes it.