No, it's not possible to indulge in an addiction in moderation indefinitely. By definition, that's not the way an addiction works.
I can smoke occasionally. I basically enjoy it until I start to get a cough. Then I probably finish up the pack I have, which lasts me over a week, and then I don't buy another pack for a long time. I'm not addicted to cigarettes. Which is not to say I won't have a headache from nicotine withdrawal, but it's not going to make me want to run out and buy another pack.