What user exist we maintain if payment receiving method is debit card or credit card ?

Dear Fi gurus

i am sd consultant , i want to know one thing regarding Userexist program while receiving payment via debit card or credit card or coupons from the customer , what user exist we will maintain

ex: in big bazar like malls payment receiving transactions will be made by both ( money and debit card or credit card ) so then this is not possible in sap so what user exist we have to maintain