N.C. Gen. Stat. § 54-68
In case the holder of any bond outstanding shall not have presented the same for payment within the period of two years after its maturity or within two years after the date fixed for the redemption, as the case may be, then such bonds shall cease to be a lien upon the mortgages, moneys, and securities pledged to the State Treasurer and deposited with him as security therefor, but such bond shall still constitute, until the statute of limitation running against such bonds shall have expired, a single legal money claim or demand against the land mortgage association issuing the same, and be recoverable from it in a suit at law, and in no event shall any interest be collectible upon such bond after the maturity thereof or after the date fixed for its redemption.
N.C. Gen. Stat. § 54-68