The app version is like an edition for a book. To find the version, go to your device’s Settings, find the app in the app list, go into the app’s settings.
You will need:
Format:
Originator/author’s surname, Initials or Corporate author if ascertainable otherwise use the title. (Year or release date). Title of app [Mobile app]. Version number. Available from: Download location [Downloaded day month year].
Example:
NHS Choices (2017) Change4life smart recipes [Mobile app]. Version 2.1.2. Available from: iTunes [Downloaded 28 May 2019]
In-text citation: (NHS Choices, 2017)