To use store credit you must create an account with us. That is so the store credit can be applied to your specific account for your next purchase. The store credit can only be used on a seperate transaction and can't be applied to the initial order or transaction. However there is a time limit of 30 days that the credit can be used. Store credit will expire in 30 days from the date it was applied to your account and will no longer be available after that. If you have questions please let me know. Thank you and Happy shopping.