hipflasker-
5mb is the amount of data that you are allowed to receive.
A smaller program will occupy less memory on your device, but has nothing to do with how much data you receive when viewing a web page or the like.
5mb is awfully skimpy – it will easily be exceeded unless you turn off al graphics (not sure how that works with a smartphone), and quite likely will be exceeded even if your phone is used for text only web viewing.
Is there a meter that allows you to guage your usage?