Ok, sort of
At first I thought this app was perfect until I started to use it more. After I bought the full version to get rid of the ads ( did not work) and enable the custom counters I found it has some hiccups. In the custom counters when you create them there is no adjustment allowed like in the monthly counter. After I created several counters I found that the end date/time I put in was always removed and if you attempted to fix it, it zeroed your counter and still did not show the date change or addition. I am hoping for a fix but this is a recent thing for me.
In general it works as advertised: it keeps track of your monthly data and wifi use of your device on a monthly basis. If that is all you need I can recommend this app to you. If you are wanting something you can fine tune and use to create the custom counters it also advertises I would keep looking or settle for the restrictions this one places on your counters.
MBIRcont about
Data Manager - Monitor Data Usage, v2.13