§ 613. Agreement of the state. The state does pledge to and agree with the holders of any and all bonds and notes of the corporation that the state will not authorize any officer or agency of government, other than the corporation, or any private person, to conduct off-track betting in the city on horse races, nor in any manner limit or alter the rights hereby vested in the corporation to fulfill the terms of any agreements made with the said holders, or in any way impair the rights and remedies of such holders until the bonds and notes, together with the interest thereon, interest on any unpaid installments of interest, and all costs and expenses in connection with any action or proceeding by or on behalf of such holders, are fully met and discharged. The corporation is authorized to include this pledge and agreement of the state in any agreement with the holders of such bonds or notes.