If I was a secret immortal how long could I keep the same US ID for before I get taken away for study. I'm thinking 150 years.

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.