All leases and permits are subject to the conditions that the lessee or permittee—
(a) must keep all buildings and other structures on the lease land or permit land in a good and substantial state of repair; and
(b) must not erect on the lease land or permit land a building or other structure that is not consistent with—(i) for a lease—the purpose for which the lease was originally issued or, if the purpose is changed under section 154 , the purpose of the lease as changed; or(ii) for a permit—the purpose for which the permit was issued.