What exactly do you mean by "credit"?
Cash credit, membership plan, add-ons?
If you mean cash credit then as long as your account is active it remains available for use.
If you mean membership or add-ons then, once active, they last a specific period of time (e.g. a month).
Please clarify exactly what you're asking here and explain clearly what sort of scenario you are interested in.
If you need to contact 48 support about this then see the links in my signature below.
