Once they have the software, they'll replace the developer who wrote it (i.e. you). Maybe ask for a real amount of money upfront instead of getting money until

Once they have the software, they'll replace the developer who wrote it (i.e. you). Maybe ask for a real amount of money upfront instead of getting money until they find out how to stop giving money (like "we don't need you anymore" or "we don't use it").