It shall be unlawful for any purchaser of oil or gas to enter into any contract with any lessee or operator under any oil, gas, or mineral lease, whereby the purchaser undertakes to pay any of the cost or expense of operation or production, steaming, treating, or running oil or gas or any other bonus or premium under any name or subterfuge whatsoever, without providing for paying to the royalty interest its proportionate share according to interest therein.