You can easily see cellular network data usage of every apps and services in
iOS in general). You also have the option to reset the usage counter for accounting and troubleshooting purposes.
To see the usage, launch the
Settings app by tapping on the following icon.
Then tap on the
Mobile Data menu.
Prior to iOS 10, the menu is named Cellular
Here you can see cellular related options with cellular usage for each installed applications and services just below that.
Scroll all the way down and you'll find the
Reset Statistics button which tapping that will allow you to reset the cellular data usage counter for all the apps and services.
Tap on the
Reset Statistics option to confirm your action.
Now if you go up the page again, you'll find your cellular data usage statistics has been reset.