You have no contract binding you to any terms, so I don't see what liability you have to complete the work. With no contract it sounds like you have no obligat

You have no contract binding you to any terms, so I don't see what liability you have to complete the work. With no contract it sounds like you have no obligation to give any notice, but if I were in your shoes, I'd give 30 days courtesy notice, after which point you will no longer take on that work. I can understand why they don't seem to be in a hurry to replace you -- "I don't want to do this long term" doesn't convey the same sense of urgency as "I am going to stop doing this after $date, so find someone else."