OperCrew allows you to keep track of payments received from customers, as well as monitor their debt.
To register a payment, go to the client's profile on the "Services" tab and swipe to the right on the tile with the required service. Click on the appeared button "Pay". If you want to mark several services as paid at once, then click on the needed name in the list of clients to open the context menu and select "Add payment".
In the payment registration window, select how many periods you want to mark as paid and click the "Confirm payment" button.