The words “paid” and “payed” sound completely identical in the English language. Part of what adds to the confusion of how to use these words is the fact that “-ay” words in English take a variety of endings. For example, “I say” is the present tense of “to say”, but “I said” is how it transforms in the past tense. This pattern is the same for the verb “to pay”, making “paid” the correct past tense verb. However, that does not mean “payed” is always incorrect.
It’s true that, when you talk about money, you should almost always use “paid” and not “payed”. Any kind of transaction, whether literally using monies or a figurative transaction, “paid” is still the proper word to use. For example, “I paid one dollar for a burrito”. Likewise, one could say “I paid her back for lying to me”. “Paid” is certainly the most common spelling between “paid” and “payed” that is used in the English language.
“Payed”, however, is still a correct word. Its use is predominantly in a sailing context. One example of how this is used is to describe ropes being “payed” out. “Payed” can also be used to in a financial context when the method of “paying out” can be likened to the action of “paying out” a rope in the nautical sense. This is a rather abstract application, but it is important for English speakers to realize that expressions such as “having payed out over time” are not grammatically incorrect.