Such a thing as permanent tolerance?

Just to preface this, i have been a severe alcoholic for between 15 to 20 years. I needed to have medically assisted withdrawal that took longer than expected because of complications related to my health and the severe addiction situation.

I was drinking at least a half gallon of silver rum @40% daily, before I finally called it quits. I was drinking that much daily for at least 3 to 4 years. I’ve been sober completely from alcohol and benzos for more than a few months.

Today I hit the wall and broke down and bought a fifth. I drank it over maybe 3 hours and feel/ felt nothing other than the initial stomach/ body warmth that went away in less than 2 minutes. Is there such a thing as a permatolerance? To be honest it’s the reason I quit in the first place. Why waste scratch to not get fucked up? I don’t drink for the taste.