On some Android devices there is a default feature which lets you manage, control and limit data usage on your phone/tablet. To limit mobile data usage do as follows:
1. Open Settings and then tap Mobile Data.
2. Tap "Limit mobile data usage" and confirm the warning
3. Tap the "Data usage cycle" and select "Change cycle"
4. Now specify the date of each month that usage cycle resets
5. On the usage chart, you should see Warning and Limit, and you need to set them to your desired
6. You are all set, and the mobile data usage will be limited as soon as it reaches Limit.