I'm not sure what their expected lifespan is, but they just keep collecting in the oddest places around the workplace. There are at least three balanced on little ledges and crammed into crevices in the bathroom. There is one sitting on top of the moulding around a supply closet door.
(There are actually four or more in the ladies' room. There was an extra one balanced on top of the lights that I didn't remember being in there.)
They almost look too scary to attempt to sniff to see if they're still good. What if they're industrial-strength, still good, and burn out the nostrils? What if they've picked up the inevitable scents from sitting in the bathroom? These are rather silly fears that could be avoided by using the proper chemistry trick of wafting the scent to the nose rather than getting a good snootful of the experiment in progress, but they are still concerns under consideration.
According to the packaging, the scent is allegedly "green apple", at least on some of the items. We shall see about that.