You will have a respective base quota allocated for your monthly usage depending on the rate plan you are on. 

Depending on the rate plan you are on, you will also have a certain amount of leftover base quota that can be rolled over from your previous month into your current month. 

In order to check your total monthly quota, which is inclusive of both base and rollover quota, you can go to the MyDigi usage page or dial *128# to see the balance quota left for your usage. 

Note: You will also get an SMS notification when you hit 75% of your base quota to serve as a reminder to help you purchase extra internet top-up if necessary.