Some of your online clients will choose to pay for their appointments in advance, but you need not worry - you'll still be able to see how much they've paid.
By taking a quick look at the Treatwell Pro Calendar, you're able to see who has prepaid for their appointment. When the client has paid in advance, they'll have a yellow "P" on their appointment. If you then click on the appointment card, you'll be able to see the price the client has paid under the "Notes".