BeLiv is a site that helps you save money on your phone bill. As long as you have internet access, you can use the app to monitor your data usage and get alerts when you're running low.
The app has a great design, with easy-to-read charts and graphs that show how much data each app is using. You can also set up parental controls so that children can't make purchases or change settings without an adult's approval.
The service is free for the first two months, then $9 per month after that. It's available for Android and iOS devices; BeLiv says it will soon release an app for Windows Phone 8 as well.
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