Calculate usage of your internet plan and never exceed your download limit.

Many times we download things and think that we have not exceeded the free download capacity and when the bill comes we are in great trouble. But there is a software named Tautology Bandwidth Meter that runs in our computer and gives us our daily usage and monthly usage. So if your limit is 1 GB than you can always point towards it and see how much you have used your plan.
Download from here.