Used to have some (actually, I still do, in a drawer) but gave up on them several years ago after random mysterious failures - just going dead after a few months.
I hope for their customers' sakes they have solved their reliability problem.
I have one that I had on my keyring for over a year, including during a swim in the ocean (I forgot I had it on me). It still works. Perhaps you got a bad batch?
I hope for their customers' sakes they have solved their reliability problem.