Many dealers will indeed store it for you for free when deployed.

At home, in a secure and dry garage, disconnecting the battery and placing it on a tender helps greatly, but don't be surprised if you do indeed need a new battery after 3 years.

Draining the gas tank and running the system dry is best, but often times hard to do. So fill it up with the highest octane gas you can buy, and it almost assuredly will start back up again when you return. Various stabilizers will not help as they do not last nearly long enough.

Tires flat spot on carpet about as well as they right on concrete, especially after 3 years. A stand would be better, but arguably less secure. Counter argument is tires going flat and having it then fall over. I'd go with the stand myself. But I also already have one. While the tires likely will look fine when you come back, don't be surprised if they don't ride well and need to be replaced when you return.

Storage bags are great if the garage is less than secure from rodents and weather (dampness and cold). I've used carjacket for years on my collector car, and will probably buy a zerust bag for the bike this year (damn mice).

Engine oil change is debatable. Many warnings about acids in dirty oil. Haven't run into this myself, but it's not a bad thing to change the oil before you go.

A dust covering of some type to keep the sunlight from doing UV damage to things that sit, like seats and grips and cable sheaths. Especially if stored in a carport or such and exposed to sunlight. I do see this often.

Otherwise, I'd expect you to be able to fire it up and go riding within an hour of your laying eyes upon it when you return.