^^ What he said. BUT. The current code I do not think will allow what you want if you are the one with the Treaty. ATM if the AI has the treaty you always have to pay, if you change the values to negative it will probably stop you from spamming your treaties, but you would then have the reverse effect on the AI treaties, they would pay you to take a treaty from them. (Asuming it will accept negative values)

You would probaly be best just to make all treaties only available once for x turns (like exploration treaty)