i want to install windows 8.1 on my pc

[BlastFX]

I have an old acer aspire m5 laptop from 2013 that broke down, it had windows 8.1 installed on its 2.5" wd blue hdd, I removed the hdd from the computer and salvaged whatever I could from it and I thought, what if I could somehow copy the windows onto a usb and installed it to my new PC? I was thinking to put an external case on the hdd, plugged it into another computer and extracted windows onto a USB? Is this possible, or would I need a product key still?

 

[USAFRet]

You can't copy the OS like that.

This being a laptop, that license is almost certainly an OEM license. And as such, you can't transfer that to a new PC. It is tied to that original laptop motherboard.