How long will aqua xtreme 50z last?

I'v been running this pump for over three years now,and seems to be running strong. Although I don't run it 24/7, I shut it down at night. Should I start thinking about ordering a replacement for it?

If it runs, don't worry about it. Simple as that.

The 50z is still a good performing pump. Unless you just want something quieter, then I see no reason to change it. You could always just get a cheap spare like a via aqua or something you are worried about your pump dying and leaving you high and dry.