Octopods are actually easy to keep if you have a tank set up that they like (lots of hiding places and LOTS of food), but most that stay small enough for the home aquarium have a 1-2 year lifespan, very much like sea horses.
If you have a tank set up that they DON"T like, however, color them gone....they are smart, strong, able to flow through a hole the same size as their beak, and smart enough to lift the lid on the tank to leave.
Thee's actually a website JUST for octopus fanciers, but I've lost the link...sorry.