There are many factors affecting observed LED life. For the LED element itself, cooling is the most important factor. If a LED element is not designed with a good heat sink, overheating will distroy it. I bought many LED elements myself in 2010 and installed them in my motor home's 12V DC circuits. All of them are still working, no problems, almost 10 years now.
For the 110V AC LEDs the power supply circuits are critical to LED life. A poor quality power circuit can mulfunction in any time, independent to how many hours in use. This is similar to CFLs.
