Hi,
Well, it seems two factors are in play. One is that it has a five time use limit or thirty days as a trial and versions before 4.2 have a lock bug.
I personally never use trials of any sort that do potentially irreversible things to my machines. Choices would appear to be purchase, command line or Linux rescue disk.
Little info available about the changelog that cured the bug, and the company HiHiSoft seems to introduce products as shareware and move on to other products leaving the previous products in the the hands of freeware and shareware download sites. They seem to cash the checks from purchases, but have no presence for support of older products; that may be different for registered owners as they may have a a site that is not publicly-facing. Their site only features their YouTube file software at this time.
Peace,
Clarke
PS You might try KeePass or some similar utility.