i have had mine since 1993. I replaced the ISS because of a leaky supercap. My arm was in a cast so I couldn’t replace the item myself. I bought a replacement from Scaled Instruments. The damaged one, when the arm came out of the cast , I replaced the supercap and use it now as a soil surface temperature unit for my soil station.
The anemometer I have two. the one on the top of my mast has been chugging along since 1993. Mysterious as it seems, but it does still work. I have a lower one with a wireless anemometer unit just incase the older one conks out. I am too old to take down the mast now.
I am not sure of the longevity, I think it depends on the conditions the unit is located. For Des Moines, Iowa and the weather we do have, it has survived .