I need to add a simple discount coupon input next to a PayPal button.
We have a website where people can book english lessons with a teacher. Usually they can book multiple sessions at once.
What we need is a simple coupon input that should work only when there is ONE item in the cart (which in only one lesson added to the cart) and the coupon should be useable only ONCE. Which means that the user will not be able to use the same coupon twice.
If you need further details on what we need let me know!