Do you mean cash credit?
It can be used to pay for services that are not covered by monthly membership plan allowances.
Monthly membership plans cover most services - e.g. see here:
But not some others - e.g. see here:
You can also use cash credit to buy membership plans and add-ons.
If you have enough cash credit on your account to cover the cost of the membership plan or add-on that you're buying then at checkout time you should get the option to pay using cash credit rather than card.
If that doesn't answer your question then please clarify what exactly is still unclear.
If you need to contact 48 support about this then see the links in my signature below.
