App Auto Updates? Choose the time when yourself!

If you have opened apps in the background, which update continuously, your internet bundle may be over very quickly. Activate the option of updating apps only when you're connected to Wi-Fi. This could save your internet and lengthen batery longevity.

Android:  Google Play > Settings> General > Auto-update apps > Make sure that Auto-update apps over Wi-Fi only is ON.

iOS: Go to Settings > iTunes & App Store > Make sure that the option  "Use Cellular Data" is OFF.