Sometimes it may take some time for the store to acknowledge the payment. Please wait a couple of minutes and then restart the app. The phone must have an internet connection to acknowledge the payment transaction.

iPhone SE, iPhone 8 and earlier, and iPod touch

Double-click the Home button to show your most recently used apps.
Swipe right or left to find the app that you want to close.
Swipe up on the app’s preview to close the app.

iPhone X and later

From the Home Screen, swipe up from the bottom of the screen and pause in the middle of the screen.
Swipe right or left to find the app that you want to close.
Swipe up on the app’s preview to close the app.

Instructions for iOS (iPhone or iPad):
https://support.apple.com/en-us/118428

Instructions for Android:
https://support.google.com/googleplay/answer/7018481?hl=en-GB&co=GENIE.Platform%3DAndroid&oco=1

If you have chosen a security code, it is only required when the app has been turned off or inactive for a longer period of time. Only putting the app in the background for a short period will not be enough.

This can occur if the app does not have access to unrestricted data usage. To allow this, follow the steps below.

1. Long press on the app’s icon and tap on the info icon in the menu that appears.

2. Go to Mobile data/Data usage and enable the switches for Background data and Unrestricted data usage.