Really? Don't certain parts have limited use? Like little nodes or transistors or something that can't function after x amount of hours.
nope, not really...
thermal cycling can cause solder joints to fracture, too high ambient temps can dry up the elcos, high current densities can cause electromicration in the metallic conductors on dies leading to open circuits or shorts, etc... but nothing really has a 'best used before date' stamped on them