You are confused & it's not your fault. The VDH web site is woefully out of date & much
of what you read might have been true 6, 7, 8 years ago but no longer. For more up to
date information, start here:
https://groups.google.com/g/video-downloadhelper-q-and-a/c/BzPLK2YyL-s
You will probably want to bookmark that one for easy reference. I recommend you read
that entire thread, if not now, eventually. As you read through that thread, you will
come across a reference to an extensive discussion of the VDH license (note: no mention
of "converter") with a link you should click. To skip quickly to that reference, do a
string search on "philosophy" in there. That will reposition the web page on the
relevant reference.
Unlock the ability to download audio with videos? Yes, you have been sorely misled. I
don't know when that was ever an issue but it certainly is not one now. Even if you
don't have a license, your downloads will have audio.
As for a "conversion feature," that is yet another obsolete reference that has led you
into confusion. Read the reference to the license I just mentioned & things should
become a lot clearer.