A lease may be for a fixed period, and so long thereafter as minerals, oil, gas or other hydrocarbon substances or geothermal resources are produced in paying quantities from the property leased or mining or drilling operations are conducted thereon, and, if the lease provides for the payment of a shut-in royalty, so long as such royalty is paid, and, if the land covered by the lease is included in an agreement with lessees, operators or owners of other lands for cooperative development or unit operation of a larger area including the leased lands, so long as oil, gas or other hydrocarbon substances or geothermal resources are produced in paying quantities from any of the lands included in any such agreement or drilling operations are conducted thereon.