Way to load an old windows hard drive in boot camp?
Windows licenses, unlike Mac, do not belong to the person but to the machine. They are not transferrable between machines.

Sometimes just changing a hard drive or graphics card would be enough to trigger the 'you appear to be using a different computer' warning, needing you to ring Microsoft to re-authorise.

So, aside from any actual surmountable issues of persuading Windows to run from an external drive [which only Windows 10 will do, iirc] or setting up a fresh Boot Camp partition then making a bare-metal backup/restore to it using Acronis [the only software I know of that can move a Windows install between different physical hardware &amp; still have it arrive in a bootable state] - once it arrives it will not be licensed.

You could, I suppose, at that point buy a new license.