Pay as you go question?

[sonic]

I have a virgin mobile cell & I have 30.$ worth of time left ,,i dont use it very often & it expires in 2 wks.. what will happen? do i need to keep "topping" it off?

[Macross_Freek]

I believe for all pay as you go services you need to top off before the balance expires in order to retain your balance. If you don't, the balance will be gone when it expires.

[sonic]

Can someone explain how registering your credit card works? How much $ do they take from your account & transfer to your phone?...I want the "smallest" amount taken. & does it EVER expire?