It's an amazing service but the more I use it the more I become reliant on it. As it stands I don't have any justifiable expectation that they will continue to

It's an amazing service but the more I use it the more I become reliant on it. As it stands I don't have any justifiable expectation that they will continue to provide the service to me which makes me nervous. I use it for a lot of smaller projects but am sometimes uncomfortable using it for larger, longer term ones due to the lack of any sort of contractual relationship. It's not that I really think they're going to stop providing it at a moments notice - those guys have a great track record - but paying for it (or having the option to) would provide that extra layer of reassurance that I can expect a given level of service.