Write to me directly. I build the app and I read the mail myself.
The app version, your iPhone's iOS version, and what you were doing at the time. If you use the Contact support link inside the app, those three are filled in for you — and you can see exactly what you are sending before it goes.
Purchases go through Apple. If you moved to a new device or your purchase is missing, Restore purchases in the app brings back anything bought with the same Apple Account.
Refunds and receipts are handled by Apple: reportaproblem.apple.com
To cancel a club membership, use Apple's screen: apps.apple.com/account/subscriptions
Your brew log, recipes and notes stay on your phone.