So, letting people try it out it for two weeks prevented them from buying it? That doesn't reflect well on customer satisfaction.
I think more than anything it reflects on the fact that most people don't need to record audio all that often. If the product is fine, but you've done all the recording you need, why would you buy it. I would wager that most users never even saw the trial end nag screen simply because they didn't need to open the app anymore.
This. It's not an app that you would necessarily use every day, so basing the trial on a certain number of days wasn't a good fit.