there is no true life expectancy on a microsd card. It all depends how often it is used. Most will be damaged long before the read/write cycle wears them out. You can find all sorts of info about this with a simple online search.
I am wondering if there have been studies that show how often one should expect to replace the microSD card in one's phone or other electronic gadget (GPS, camera, tablet, whatever).
I know lots of people have their particular "behaviors" they think might/must improve the life of the chip - but any facts from specialists who have studied the topic?