Wiktionary
n. (context US English) A job in which one remains for one's whole career until one's retirement.
Usage examples of "lifetime job".
The situation tended to make keeping an agent loyal a big problem, since there was nothing he or she could be offered as a reward and it was a lifetime job.
She accepted a once-in-a-lifetime job offer and went away, and now she was married to some super-terranean that took her on cruises through the rings of Saturn and was wealthy beyond belief.
The frontier outpost that's supposed to be the steppingstone to bigger things turns out to be a lifetime job.
McDonald could be completely innocent, and we could be screwing him out of his lifetime job.
I mean, I was over forty with a guaranteed lifetime job in one of Earth's better, if stuffier, universities when I decided to enter Starfleet Academy and start a second career.