Is it possible to find out an app download / installation date on iOS?

Solution 1:

On iPhone (iOS 11.0.3): Settings > iTunes & App Store: Apple ID: View Apple ID > Purchase History -- tap "Last 90 Days" to expand view to include previous years.

Shows free and paid purchases by date.

Solution 2:

There are some dates you can see in iTunes. Perhaps apps downloaded directly to the iPhone are not there? I don't know.

Solution 3:

In the older software, there is no way of finding out exactly when an app was purchased, but in the latest software, you can go to the App Store and select Updates, then click on the top right to go to Purchased and see if the app was purchased (paid or free) and the date of install.The list is sorted by newest on the top.