Sections 376.630 to 376.650 shall not be applicable in the following cases, to wit: If the policy shall contain a provision for an unconditional surrender value, at least equal to the net single premium, for the temporary insurance provided for herein, or for the unconditional commutation of the policy for nonforfeitable paid-up insurance, or if the legal holder of the policy shall, within sixty days after default of premium, surrender the policy and accept from the company another form of policy, or if the policy shall be surrendered to the company for a consideration adequate in the judgment of the legal holder thereof, then, and in any of the foregoing cases, sections 376.010 to 376.670 shall not be applicable; provided, that in no instance shall a policy be forfeited for nonpayment of premiums after the payment of three annual payments thereon; but in all instances where three annual premiums shall have been paid on a policy of insurance, the holder of such policy shall be entitled to paid-up or extended insurance, the net value of which shall be equal to that provided for in sections 376.010 to 376.670; provided further, that this section and sections 376.630 to 376.650 shall apply only to policies of life insurance issued prior to the operative date of section 376.670.