I've got one, actually a 6" desktop, that I've been using for over 3 years, at least 8 hours a day.
It has gotten sticky a couple times, but the trick to saving the small motors on those is maybe once a week, with the fan off, spin it by hand, and if you feel increased resistance, shoot a little Deep Creep or WD40 on the front and back of the shaft, letting it run into the bearings.
Then spin it again, and you will notice it loosened up for another month or so.