Haven't registered a deposit? See this guide
Did your client not show up? See this guide for forfeiting the deposit
1. Open the calendar and click the session you have with the client
2. Click Checkout at the bottom
(When the client has a deposit/credit, it says Open credit next to their name)
3. Control that the Final Price is correct and click Add Payment
(If the final price is higher than the deposit, you can adjust the Final Price)
5. Click Use client credit and click Complete checkout
Since the client already has $150 in deposit, and the session is $150 the client doesn't need to pay any extra.
(If the final price is higher than the deposit i.e $170, you will get the option to get paid $20 online or cash from the client in this window)