Using with only room-temp solutions and wort and storing in a good storage solution, should easily provide many years of service. I just replaced my old probe from my MW-101 after about 7 years of service. Of course, I'm only brewing maybe 6 or 7 times a year, but you get the idea of its overall use.
When used in a commercial brewery setting with daily brewing, I'd say that a year could be about it.