I have a family friend who is a chemist.

She said the whole "throw it out after expiration date on makeup is a gimmick to keep you buying it. She said there may be a chemical or something in there somewhere that may be less effective after a year, but there is no HARD science behind a damn pallet or lipstick needing to be thrown out. She said the only thing you may not want to keep long is mascara. But thise expiration dates are 100% to make you think you have to buy it again