There is no way to stop unless you are doing illegal works like selling books for your own need without resell rights. I would suggest to post your idea and thoughts here in this forums so someone can suggest you better answer.I've thought about using the affiliate program with a bookstore on my blog, especially since my blog is literature based. But I haven't tried it yet. Can anyone tell me if you are allowed to start and stop that whenever you want? Are there penalties for stopping the program once you've started?