A client was looking to implement an ERP for his business. He wanted everything but he didn't want to pay much money, a classic. In the end we agreed on a budget that was comfortable for both.At some point in the negotiation he blatantly mentioned "I don't trust you, I would like to split payment into monthly installments and be able to cancel anytime, no strings attached". Despite this massive red flag I decided to go through (won't do it again, ever) and we sign a contract with that clause, which turned out to be my lifesaver.The guy was a complete [REDACTED], we were delivering progress way ahead of time and he was always complaining about one thing or another, and kept adding requirements that were not there, threatening us to dump the whole thing because of the clause.Two months in we had enough, I called for a meeting with him and his team, then proceeded to invoke the clause on my favor, he was very pissed off to find out that it could actually be used against him, but ¯\_(ツ)_/¯. We parted ways that evening and haven't looked back ever since. So long man, let's never meet again.