The phrase "one's many years" refers to a person's lifetime or duration of existence. It can also imply that someone has lived for an extended period, and has accumulated a significant amount of experience over time.
It was a fire sale and I got a couple of years of salary. (businessinsider.com)
We came very close to booking as much business this quarter as we did for all of last year for engineered systems. (seekingalpha.com)
You can tell based on the fabric composition and feel that these pieces are durable and can last for years of sleeping and lounging. (businessinsider.com)