The free version is important as a trial: I would never have bought instapaper if it were not for it. What I think, though, is that perhaps what most paid apps

The free version is important as a trial: I would never have bought instapaper if it were not for it. What I think, though, is that perhaps what most paid apps need is a way to do "shareware": allow the user to try for a day or a week, and then let apple block the app from working until the user buys it. There are a lot of apps that I would buy under this model that I don't due to fear/uncertainty/doubt (and in-app purchases for features don't really work for the same reason that I never know if those features are actually worth the cash, unless it's "pay me to stop bugging you with ads", which is really annoying).