When using the integrated credit card processing feature you can send a link to your clients that will take them to an online payment page.
From this page they will be able to see when their remaining balance will be due. Underneath that they can tick a box that says "Charge this card on that date".
This will allow your client's card to automatically be charged on the final balance due date saving them from remembering or you from having to track down that final payment.
You can also toggle this option on or off by going to your client's order.
Select the "Payments" tab.
Click on "Update Payment Options" in the bottom right.
A pop up window will appear allowing you to tick or untick the Auto payment feature as well as the card that will be charged if there are more than one on file for the order.
This can be helpful in case your client ticks the auto pay box on the online payment page on accident and you need to change it back to a manual payment.