The lessee shall agree (a) to drill and produce all wells necessary to offset or protect the leased land from drainage by wells on adjoining lands not the property of the lessor, or in lieu thereof, compensate the lessor in full each month for the estimated loss of royalty through drainage: Provided, That during the period of supervision by the Secretary of the Interior, the necessity for offset wells shall be determined by the supervisor and payment in lieu of drilling and producing shall be with the consent of, and in an amount determined by the Secretary of the Interior; (b) at the election of the lessee to drill and produce other wells: Provided, That the right to drill and produce such other wells shall be subject to any system of well spacing or production allotments authorized and approved under the applicable law or regulations, approved by the Secretary of the Interior and affecting the field or area in which the leased lands are situated; and (c) if the lessee elects not to drill and produce such other wells for any period the Secretary of the Interior may, within 10 days after due notice in writing, either require the drilling and production of such wells to the number necessary, in his opinion, to insure reasonable diligence in the development and operation of the property, or may in lieu of such additional diligent drilling and production require the payment on and after the first anniversary date of the lease of not to exceed $1 per acre per annum, which sum shall be in addition to any rental or royalty herein specified.