RGB-LED's pretty much run forever. Though over time the light output will slowly get lower. Most LED's all have about the same specs for hours, which is about 80% of initial brightness at 30,000 hours, and 70% around 50,000 hours. This is accurate for Minleon LED's.
But just as important is the temperature the RGB-LED's are running at. Higher temperatures will reduce the output faster. Minleon controls the power to our RGB-LED's in software which limits the maximum temperature, thus extending the lifetime. This is one of our competitive advantages.
Most likely something else will fail long before the LED's are a problem. This is why Minleon over the years has bulked up it's wiring, improved the water-tightness of its base & switched to Twist-&-Lock connectors for all strings & connectors in 2017's RGB Plus Line.
Running hours for a typical application:
50,000 hours = 2083 days or 8 years of 24-hour run-time at full brightness.
If used only 12 hours a day with typical effects they will last 3-6 times longer, or 24-48 years.
Decorative Strings: C7's, G40's...