N.C. Gen. Stat. § 7A-316

A witness in a criminal action who is entitled to a witness fee and who proves his attendance prior to assessment of the bill of costs shall be paid by the clerk from State funds and the amount disbursed shall be assessed in the bill of costs. When the State is liable for the fee, a witness who proves his attendance not later than the last day of court in the week in which the trial was completed shall be paid by the clerk from State funds. If more than two witnesses shall be subpoenaed, bound over, or recognized, to prove a single material fact, disbursements to such additional witnesses shall be charged against the party issuing or requesting the subpoena.