Anyone know of a small, free network traffic monitor?

At work, I use my iPhone as ripe for my Aspire One with win8.1, and I'm a bit in trouble late in the month since I only have 3 Gbyte data Included in the my mobilabb. So I would like a meter that measures the traffic and writes a log or otherwise can display the total consumption.
The prg I have found is either payment programs, or they are too complicated, something with packet analysis, host-analysis,., And I will just measure and store how many mb in / out from my iPhone.