Well, if you are not aware of the fact that how much data do you use in a month, in a span of 7 days or in a day, WeeTrackData via Cydia lets you know every stat. It is widget which would appear in the notification center and remain there all the time whether you see it or not. All you need to do is to turn it ON from settings>notification center>WeeTrackData.
Do remember that the sequence of the widget arranged in the notification center depends on the way you turned them ON one by one. If you turn ON, weather widget first, it would appear on the top followed by others. After turning WeeTrackData ON, pull the notification center down from the status bar and checkout the monthly stats of both sending and receiving data.
At the end of the month, you can also checkout the total data used mentioned at the same place. Just slide right to left and stats for last 7 days would appear. It works on the same principle. If you want to know the data used in a particular day, slide again and you will be able to see the data used in a day. You can also customize about ‘monthly limit(mb)’ and ‘billing cycle starts every’ from the settings.app.
WeeTrackData can be purchased from the Cydia Store at a price of $1.99. You should definitely try this widget if you are want to track your data usage on iPhone. Let’s know if you have already used this widget in the comment section.