Do I collect user sensitive data for aggregation analysis like most Android apps?
I physically can't. I have nowhere to store it. I don't have a server database to store it. I value privacy as much as you do and I disapprove global mass surveillance, so even if Audrey Tautou asked me nicely to see your data, I would not have anything to show her. That's why I believe in opensource software and that's the reason why, with Ad-Free, what happens on your device stays on your device.
Figure out how Ad-Free works and dig into the code at https://github.com/abertschi/ad-free
P.S.: In case you have never heard of Audrey Tautou (for some inexplicable reasons), she is a very beautiful French actress. She played in movies such as Amélie or The Da Vinci Code.