In my experience with laptop computers the laptop computers for me only last 4 years.
At 4 years they completely go out on me and won't even turn back on.
So plan on replacing your laptop computer at around 4 years but if you're lucky it might last longer.
On desktop computers I can get over 10 years of life out of a desktop computer before needing to upgrade and sometimes they're still working but things are getting outdated on the desktop so I upgrade at around 10 years.