- "Your latinum is always welcome, but if you want credit you'll have to talk to the owner".
Credit was the act of allowing a person to purchase something without paying money or another form of currency (such as replicator rations) for the item, with the promise of paying it back to the creditor. A line of credit was one's own personal credit account.
After he ran out of money, Kozak wanted to buy more bloodwine with credit, something which Quark was not open to, as his bar was not as profitable as it had been at the time. (DS9: "The House of Quark")