Yes. Quit21 has no account, no server, and no data collection. Everything stays on your device. See the Privacy Policy.
Open Settings inside the app. "Export My Data" saves a JSON or CSV file you choose where to keep. "Delete My Data" permanently removes everything from your device.
Make sure you're signed in with the same Apple Account you purchased with, then relaunch the app — Apple restores your purchase automatically since Quit21 uses no separate in-app purchase.
No. See the Medical Disclaimer. Please speak with a healthcare professional about your own situation.
Email mailtohukam@gmail.com with your device and iOS version.