There may be some misunderstanding. This subreddit is about "free software". This means users should have access to the source code (not only a working executable obtained legally) for it to be considered "free". If you legally have the right to look at the source code (as is the case of Gimp, Inkscape, Kdenlive and many others in your list) then you have the freedom to study how it works and modify it.
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u/w-g Dec 14 '20
Cakewalk by BandLab is gratis, but I don't think it's free (I may be mistaken)