How do you know when it's time for a new laptop? 7 years old machine [View all]

It's an hp "Envy" - and the only real problem was buying a new battery a year or two ago, had to go through an outside-from-hp warehouser.

What prompts this is that in the past week the (fan?) seems to be on much more and louder. "Louder" not meaning like rattling or clanking, just higher level of fan-sound. And right now almost constant.

Now. I use this machine on a completely well ventilated rolling little table of metal rungs like refrigerator shelves, meaning NO sealed off surface blocking the ventilation. Also, ONLY there, never taking it anywhere. It's like a stationary/desktop. Plus, I always unplug it upon logging/powering off.

So far, for over 30 minutes the fan has not gone off. 7 years, is it time?

ON EDIT: 45 minutes and it's humming/buzzing - maybe not a fan? Is it the (motor?)?