I have some night lights that have been on continuously for over 15 years.
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Pentagonlight
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Red LED on a teevee in an almost-never-used room that I never got arsed enough to unplug (gotta move a heavy dresser away from the wall to get at).
Gotta be at least ~25yo at this point. Few years before 9-11, so 1990something.
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The red LED digital display on a (Radio Shack) Realistic Chronomatic 263 model 12-1573 clock radio thatâs been on my nightstand for decades. I run it on âdimâ so, not driven hard.
Only been âOFFâ during power failures.
Thereâs a date code stamped crooked on a small paper tag of 7Al . Canât ascertain if the last character is a lower case âLâ or a truncated upper case âLâ. Def not a â1â. August '87 maybe?
We had it when we moved into our current house in 1993, but I donât remember when I bought it prior to that.
Some interwebs chatter indicates it appears in the 1991 RS catalog.
Wife thinks I had it when we met 1986-ish, but those were our psychedelic-drug-induced days, so it might have appeared then from an alternate reality & somehow gotten stuck in this one.
8760 hours x 25 years = 219,000 hours.
Guessing led uses 0.2W.
= 48kw/h 
1987, damn impressive.
Impressive numbers.
red LED on the smoke alarm.
only off to change the battery.
at least 30 years.
There are some impressively old LEDs in this thread.
It got me looking around to see what my oldest ones are⌠but I did a tech refresh a few years ago which retired my oldest devices which had been in continuous operation.
I think the longest Iâve had a LED on continuously was about 20 years⌠until I finally retired that server. The LEDs still worked fine, and the CPU and RAM and hard drive and stuff⌠but a critical ethernet port died and I decided to replace the entire box with something modern since even a raspberry pi would be much, much faster.
As for items which are still running, I think a couple of my devices have been running about 15 years now. Or about 10 years for âjust a lightâ which isnât part of some other device. I got some USB lights and one has been providing a gentle glow / nightlight in my office for a decade.
My car voltmeter with 7 segment blue led numbers - always on for about 15-16 years.
One segment has failed but I still use it because it is usable but I compare it with the same unused multimeter and see that it loose much of light intensity for 15 years.
My hallway night light is right around the same vintage, bought in 2008. 3 sort of cringy purple tint LEDs that barely illuminate the hallway. I remember doing a calculation of how much it would cost to run them at $0.05 a kWhr for a year and it was pretty cheap. To bad we now pay up to $0.54 a kWhr now . . . .
Not exactly running, but I have the lightup modules from a pair of black nikes with red blinkies from my childhood. The blinkies still work, itâs basically the same tech in dog toys. In my opinion, non-tactical emergency response teams should all have blinky modules in their shoesâŚitâs non glarey, and usually sits below any smokeline.
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Maybe make LED versions of Al Bundy Shoe-Lights. 
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