Sorry to hear, always sad to lose a love one.
I've always had cats and dogs from when I was born. Currently my wife and I have one cat (Bud) he is very smart, smarter than some humans lol. When he was young he could easily turn the lights off/on /off/on and open the kitchen cupboards to raid the food. He could easily jump on top of the fridge and like to rest on top of the kitchen cupboards (way above the bench tops.) He is getting old now (16) and has settled down a lot, can no longer jump on top of the fridge, the cupboards or turn the lights off and on.