( first , i am not good in english well but just i want to help you , so plz understand my bad english :P )
i will introduce some example...!
A : my love , how much do you love me ?
B : i love you as much as sky !
A : 자기야 , 나 얼마나 사랑해?
B : 하늘만큼 사랑해 !
so you can understand 만큼 mean like ' as much as '
휴대폰 요금은 사용하는 만큼 나와요
cell phone bill will fee as much as you use