billing confusion

i have my aunt's userid & password she gave coz she is going to US so that i can use even her bandwidth. The question is when i use the internet using her id & download software will i be billed extra for downloading more than 1gb or will she be billedi read this somewhere Chances of using " someones " userid and password is ruled out as Broadband connection has been tied with your home phone number + userid. Hence no need to worry.