This depends on the host. Each host sets how much they want to charge per night, per week and per month.
When booking, you pay a 15% booking fee to Homestay.com to secure the booking (maximum of 199 $£€ for longer term bookings). You then pay the total price of stay owing directly to your host, either on arrival or in advance depending on host preferences.
The booking fee is automatically calculated on the total price of stay and included in the booking payment information.