Sales commission
A sales commission is the percentage a platform takes on each transaction, usually plus a fixed amount. It grows with your revenue: the more you sell, the more you pay.
It is the dominant model in Latin American markets, with rates typically between 5% and 10% plus a fixed fee per order.
The blind spot is the long run. At 9%, doubling revenue doubles what you pay; on a flat plan the cost does not move. The crossover usually arrives sooner than people expect.