Remember when you opened it.
Please include your iPhone model, iOS version, app version, and a short description of what happened.
Open iOS Settings → Notifications → Opened and confirm notifications are allowed. Then check that reminders are enabled inside Opened.
Opened stores data locally on the device. Use Export CSV before deleting the app if you want to keep a separate copy.
Open the Pro screen and choose Restore Purchases while signed into the Apple ID used for the purchase.