I only started training a couple of years back. Alfie wasn't my biggest fan at the time so it helped us work together and regain some trust from each other. I must admit I've slacked off recently and we haven't done much training at all, but he still remembers everything he learned previously.
I attempted to do that same training with Greycie, chopstick and clicker too. The one that really stuck was the spin. She now spins whenever I have something she wants. And she'll keep doing it until she gets it. Training gone awry.