When a booking comes from Booking.com, Airbnb or another connected channel through Johku's channel manager, Johku charges no commission on it. You can sell in all the channels where your guests are, and Johku's cost does not grow with your channel sales.
What you pay for and what you do not
The channel manager has a fixed monthly price that is based on the connected properties, not on the number or value of bookings. The channel's own commission is an agreement between you and the channel, and Johku does not change it.
Compare this point carefully
If a system also charges commission on channel bookings, you pay a commission on the same booking twice: to the channel and to the system. So when you compare systems, ask separately whether the commission also applies to bookings that come through channels.
You can see Johku's commissions and monthly prices on the pricing page, and the channel manager's prices on its own page.