When someone gives you a hand, you have to show gratitude. Every. Single. Time. Whether it’s some advice, an introduction to someone else, or giving the best gesture they can, of using your creation (ie. your product), you’ve got to appreciate it. As a startup, you’re effectively saying I want you to trust me, someone you may not have ever met, with solving your problem. And so when they do it, you owe it to them for giving it a shot.