May need to change the rotors and or have the calipers checked for lack of free movement. The brake caliper must do what is called "float" that is that it can move freely on its pins to put equal pressure on each side of the brake pad against the brake rotor. If it cannot move freely then it will eat up the brake pads in a short time, usually it will eat up one side and not the other side of the brake pads.
Bad brake rotors will cause the pads life to be shortened. That could be caused by the rotors being out of true (wobble feeling, usually a pulsating brake pedal while stopping), or the rotors having very rough areas that just shred the brake pads while trying to stop the car.
And last if you drive with your left foot on the brake or do very hard fast stops all of the time that will just plain wear out the brakes and also cause you to have to use more fuel because the car is not only trying to move but at the same time trying to stop also.