Shift a 40 bit number into the chip with the two inputs data (IN0) and clk (IN1). If the shifted 40 bit match the hardcoded internal 40 bit, then and only then the output will become high. Having only the mikrochip without the design files, one might need reverse engineering and/or side channel attacks to fing the correct 40 bit.
Get the correct 40 bit from the design and shift them into the shiftregister. Each rising edge at the clk will push the next bit into the register. At the correct 40 bit, the output will enable high.