Although it is not new to some Android users but still some android users are not aware that they can manage and control their data usage as well set their data limit. For example You have 6gb that will last for 3 months and you decide to use 2gb each month. What you need to do is to set your data limit to 2gb. The moment your data has reached 2gb, you will be notified and your data will automatically be turned off.
This is how to set up your data limit
1. Make sure your data is on. Goto your settings
2. Swipe to the left.
Click on Data Usage
3. Tick Set Mobile Data Limit.
A pop up will appear as shown below. Click on OK
4. Now drag the line till it reads the limit. The limit used as an example in the pics below is 1.5gb
You have successfully set your mobile limit