1
general::
Also, extend someone credit. Allow a purchase on credit; also, per mit someone to owe money. For example, The store is closing your charge account; they won't extend credit to you any more, or The normal procedure is to extend you credit for three months, and after that we charge interest. This idiom uses the verb extend in the sense of ‘‘offer" or "provide," a usage dating from the mid-1500s.
American Heritage Idioms