Do you keep your light on constantly?
I used to have a lamp that I kept replacing bulbs for "all the time". I didn't understand why since the light bulbs claimed to last for years and years. One day I read the light bulb package more closely, and it said something along the lines of, "7 years life span at 2 hours per day" in small text (the numbers may be wrong, going by memory). Doing the math, the number of active hours claimed on the box turned out to be roughly true. I don't know if LED bulb packages play similar tricks but it's worth checking out.