Email a.negovskiy@gmail.com. Tell me your iPhone model, iOS version and the app version.
Apple Watch (Series 3 or later) estimates VO₂ max during outdoor walks, runs and hikes recorded in the Workout app. Indoor workouts and other workout apps don't add readings. A first reading can take a day of wear and a few outdoor workouts.
If readings exist in the Health app but not in VO2 max Hero, open the Health app, tap your profile picture › Apps › VO2 max Hero and turn on Cardio Fitness.
Manage or cancel in iPhone Settings › your name › Subscriptions. Cancel at least 24 hours before the period ends to avoid the next charge.
Bought Pro on another iPhone or reinstalled? Open Settings in the app and tap Restore Purchases.
Refunds go through Apple: reportaproblem.apple.com.
What the app reads, what leaves your iPhone and how to delete it is in the Privacy Policy.