Verizon data plan?

[Indigo Love!]

I just got my first smart phone several days ago. Last night I check my data and it says I have used up 0.305 Mb out of 2 g. I have been trying to close out all apps if I use them and not go on them for a while either. I also use wifi when I'm at someones house too to help preserve data. My sister told me today that if I don't turn off my 4g lite network it can suck up data. I honestly didn't mean to be so careless. Will my mom be charged extra or just the 40 dollars a month she pays. We both share a plan so its actually good to teach myself how to use something sparingly. Will my mom be charged extra?