The reviews are right about not being able to cancel. The app isnt worth paying $2.99 for and the advertisement for it was over the top.... NOT worth the hassle, but if you go in your email, youll get the Apple subscription Confirmation email telling you about your recent purchase. Just open it up and youll see where it says about the "review your subscription" and you can cancel it there.
Digster13 about Yarn - Chat & Text Stories, v1.6.0