To control access to the app and its data, a passcodee can be set up in the app settings.
This code is requested when you open the app if the app has previously been closed completely or placed in the background for more than 3 minutes. The delay is deliberately chosen so that you can leave the app for a short time (e.g. to look up the price of your last online purchase in the emails) without having to enter the code immediately when you return.