How to check quota usage?

Android

Step 1: Open the Settings app

Step 2: Tap 'Connections'

Step 3: Tap 'Data Usage'

Step 4: Tap 'Mobile Data Usage'

Step 5: The top of the screen displays your data usage for the current month (as determined by your billing cycle). Tap the Date to see previous periods

Step 6: Scroll down and tap any app to find out how much data it uses and to control whether it can use Mobile Data, Wi-Fi, or both

Step 7: Go back to Data Usage and tap 'Billing Cycle" to set the date when your plan resets the monthly billing cycle.

Apple

To view overall usage, go to 'Settings' > 'Cellular' or 'Settings' > 'Mobile Data'. If you're using an iPad, you might see 'Settings' > 'Cellular Data' instead.

To view the Internet quota used by each app on your phone, scroll down. If you don't want an app to use cellular data, you can turn it off for that app. When cellular data is turned off for that app, it will only use WiFi.