We do not want your personal data. We make money by selling you an app for working with PDFs, not by mining your personal information. Therefore, we try our best to collect as little data from you as possible.
We do not collect any payment or licensing information as the purchase and delivery is handled by Apple through the Mac App Store. The App Store statistics does not give us any identifiable information and we do not require any personal information to use the app. For us to know who are customers are, the customer needs to contact us first.
Highlights gives you the option to store a username which is used for the annotations you make in the PDF, but this is only stored locally. Crash reports are anonymous and handled by Apples frameworks which requires you to opt in. We do not currently have any e-mail lists used for marketing, only lists for sending out invites to beta testers.