You should not have to buy another license, as long as you're running Firefox on both
computers. You can read some background information on the license by clicking here:
https://groups.google.com/g/video-downloadhelper-q-and-a/c/BzPLK2YyL-s
That's one you'll probably want to bookmark. Do a string search on "philosophy" in
there. That will get you another link to click. Read up on the subject. Since you are
doing multiple installs, there's the risk of your license getting locked. Another
reference in there describes what you should do in that case. Do a string search on
"revalidate" in there to find the instructions for unlocking a locked license.
Normally, I'd ask to see some screenshots but we're talking about your license. You
never never NEVER want to post your license in public. All I can say is just make sure
you're typing the license number in correctly. You can't directly copy & paste it from
one computer to another. But maybe you can copy/paste it on the old computer into an
E-mail to yourself. Then receive the E-mail on the new computer & copy/paste from there.
That would take the issue of fat-fingering out of the picture.