2GB - AT&T Data Usage Watcher

We have a AT&T data share(family) plan. Last month(Oct 2014), we were charged $15 for 8 MB data overage. so depressed, I started to look for an app that could
1. monitor family data usage
2. tells me if I am over scheduled usage so that I can limit my usage early in a billing cycle.

My AT&T is good but it requires log-in each time. Other usage monitors are great except they just monitor single device's data usage than the family plan's.

So here is this little app that helps me. I hope you find it helps you, too.