What is the life expectancy of KONI shocks?

[Ray Sta.Juana]

I have had the Motivational Coil-Over setup for a few years now and they
have about 60K miles of street driving and about 3-4 track days on them.
I'm just wondering when I should look to replacing them or what I can do to
test of they're going bad.  It's just that recently the car's ride has been
getting a little harsher than I remember but it could be just my mind
playing tricks.  Any thoughts on this? TIA

Ray S
98 Sentra SE w/mods
04 Kawi Ninja 250R w/mods