I've kept octopus a coupel of times. They do have short life spans, I don't know about 12 months, my last one lived for about 2 years. I kept mine in a 20 gallon tank. It was one of the coolest animals that I have ever had. Extreamly smart. One word of caution, aside from being able to get out through the smallest holes, they will make a meal out of any fish that's not big enough to eat them, crabs, snails, etc...I remember seeing mine eat a royal gramma, what was I thinking?
A biologist friend of mine had 2 55 gallon tanks in his class where he taught. One tank had the octopus the other had the crabs that were for food. At night the octopus would crawl out of his tank and into the other, grab a crab and bring dinner home to his tank. He thought that one of his students was doing this until he actually caught the octopus in the act.
Lesson learned; the're smart!