[CompelTechnic]

To get the fully nuanced picture: -If you wander around to a grocery store bakery, and eat one of the donuts before getting to checkout, you have the right to settle your debt with cash. -Otherwise, the store can force you to pay with their preferred method, or else will return the merchandise to the shelves.

[Chris2048]

> and eat one of the donuts before getting to checkout

I'm not sure you have a legal right to do this. I'm pretty sure consuming something that isn't your is actually theft.

[CompelTechnic]

Yeah, that's a good point. I mostly wanted to convey a payment after use of the product or service. A better example might be paying your mechanic after he finishes fixing your car.