A much-asked for and surprisingly depreciated feature may soon make a comeback with a twist in a future Windows 10 Mobile build or in the universal Windows 10 Store app update. As you can see in the leaked screenshot above soon apps will show the time when they were updated last.
It seems the Downloads and updates page will show recently updated apps in recent activity and you should be able to know when a particular app was updated last, if you have it on your device.