Led Monitors should easily last from 5 to 10 years if properly taken care of.
When not using the monitor you can extend it's life by shutting it off if you plan to be away from the led monitor longer than an hour.
I have an led monitor that I paid $85.00 for new 5 years ago and use from 8 to 10 hours per day and it's working like it was when new.
If it did quit on me now I would just go out and buy another one because for $85.00 I've gotten my money worth from it.
Manufactures claim that led monitors can last up to 15 years which is possible but likely something else will fail inside the monitor and not the led bulbs.