It’s not like there are people checking for immortals, I think it would be flagged by a dmv employee or something when they dont believe a clear 21 year old is actually 150. Let’s assume it’s current day im caught and not bring speculation on what the US is like in the year 2139 is like.
You’re looking at frequent IRS Audits and verification requests from Social Security and what not, but TBH if those people keep their mouths shut and you don’t tell anybody you’ll probably never get taken away in most developed nations.
The thing about it is you’d have a difficult time convincing anybody you’re really that age, and the companies that are capable of studying you aren’t actually competent.
You’re more likely to just get deported somewhere at random.
I appreciate your answer