Solid state electronics don't "wear out". Failures are very infrequent and basically random (assuming no electrical, mechanical, or thermal abuse). On average, 2 years should be no problem.
But if the design is critical, such as life-support, or if it's going into space where it can't be repaired/replaced, you have to take extra precaustions, because failures are random and there is a slim possibility that you get a failure after 2 days, or 2 weeks...
Take a look at this
. (That's just for the chip. Of course, there are more parts on the Arduino board, and you might be adding some parts. If you use 100 parts, life-expectancy (MTBF) is 1/100th.)
I do have an Arduino that "went bad" after a couple of weeks... The chip is running, but the bootloader doesn't work. (I don't know if the bootloader somehow got corrupted, or if the serial-chip "went bad" or somehow got burned-out.)
I built a few projects with a different microcontroller about 15 years ago, and they still work fine. One is a car alarm that's been running 24/7 for more than 15 years... even when it's not armed. The only time the microcontroler & software-loop haven't been running is when the battery was dead!
Mechanical parts (switches, relays, motors) and connectors can wear-out and connections can become corroded. Electrolytic capacitors can have lifetimes less than most other "electronics". And of course, vacuum tubes age, deteriorate, and wear-out.