You can use your subscription on another iPhone or iPad by signing in with the same Apple ID on both devices. To ensure your profile, data, and subscription sync correctly, please follow these steps:
Step 1: Enable iCloud Drive
Open "Settings" on your device.
Tap your "Apple ID" at the top.
Tap "iCloud" and make sure iCloud Drive is turned on.
Step 2: Enable iCloud sync for the app
In iCloud settings, scroll to the app list.
Find Calorie Counter app and toggle it on to allow syncing.
Step 3: Restore your subscription
Open the app and tap any paid section.
Tap "Restore" in the top-right corner.
Once restored, your subscription will sync immediately, giving you full access on all your devices.