I am convinced that cats never forget. My previous cat, Boots, never seemed to forget anything. Once, when she was around six or seven months old, I was spraying air freshener, the kind that sprays straight up, into the room. Apparently a little of the mist went into her eyes because for the rest of her life, she would blink rapidly whenever she saw a can that resembled that can. One day, also when she was young, she was on the TV table and refused to get down no matter how many times I told her to. I only sprayed one spritz of the water bottle and for the rest of her life, whenever I brought out the bottle, she would immediately stop whatever she was doing. I never had to spray her again; just the sight of the bottle made her stop.

Edited to add: My current cat, Martini, was on the TV table and I sprayed her with the water bottle about five times and she just sat there, looking at me like I was crazy. She didn't care at all.