A question where I would like to know the answer for too.
I have been running my compute stick for over a month and so far, everything still looks fine. But I have heard from others that if the "environment" is not well ventilated, the compute stick will get unstable. As I am running in a normal office environment, mine works well up to this point.
Our products are always built with high quality components so the Intel Compute Stick should work just great for an indefinite period of time but I will check internally with development what is the Lifespan of this component.
I will be back soon with more information.