If the leased premises produce gas in excess of the lessee's requirements for the development and operation of said premises, then the lessor may use sufficient gas, free of charge, for any desired school or other buildings belonging to the tribe, by making his own connections to a regulator installed, connected to the well and maintained by the lessee, and the lessee shall not be required to pay royalty on gas so used. The use of such gas shall be at the lessor's risk at all times.