On your iPhone: Settings → your name → Subscriptions → ReCal → Cancel. Cancel at least 24 hours before the trial or period ends to avoid the next charge. Deleting the app does not cancel it.
Open ReCal and tap Restore purchases on the subscription screen, or in Settings. Use the same Apple ID you subscribed with.
Your plan, logs and weigh-ins are stored only on your phone. Restoring your new iPhone from an iCloud or computer backup brings them across. You can also export a CSV any time in Settings → Export my data.
That's on purpose. Meals tagged Prep are already cooked, so ReCal never resizes them. When a day runs over, it takes from Optional items first, then Fresh meals later that day or over the next few days.
ReCal searches the USDA food database. For branded foods, use Quick add or save it once under Recipes → My foods with your usual portion.
They're estimates from standard formulas, and you can change any number in Settings → Targets. ReCal is not medical advice; check with a doctor or dietitian before big changes.