Sound Effects Credits will show up in your Shopping Cart and on your Account page. It's one credit per sfx, no matter the price.
You can choose to apply these credits to the sound effects by clicking the Apply Credits or Remove Credits button in the shopping cart.
You can download as many or as few sfx at a time as you wish. The available credits will decrease as you use them and be available until you use them up. They do not expire.
The credits are per sound effect. The price of the sound effects does not matter.
Checkout normally and the sound effects with credit applied will be instantly downloadable with no further amount due. Anything else in your cart, i.e. music, hard drive, will require purchasing to complete the order.