I found that some wordpress themes and plugins uses activation key approach, to sell GPL licensed theme. Is it illegal to remove the code logic for licensing, and redistributing them?


No, it is completely lawful, and in my opinion a public service.

The only possible argument against it would be that you're circumventing a technological protection measure, a practice which signatories to certain WIPO treaties are obliged to forbid. GPLv3 is very clear that that doesn't apply, in s3:

When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work

  • If supporting the theme involves an infrastructure expense, it would be vaguely unfair to remove the feature the hoster put in to cover their expenses. I don't think this could realistically escalate to a court case, just sayin' if you remove their activation code, maybe don't be surprised if fetching things from the original hosting service without proof of activation stops working. – tripleee Dec 17 '19 at 4:59
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    @tripleee to my mind, the unfairness is taking code that someone else wrote at least part of, which they clearly intended should be free (as in speech) indefinitely, and expecting others not to use it on that basis simply to support your business model. – MadHatter Dec 17 '19 at 7:53
  • I completely support this answer and have upvoted it accordingly; I'm just hoping to add some perspective with my comment. Charging a reasonable fee for a useful service is unproblematic even if the code that the service requires is free (in every meaning of the word). I'm not sure if that's the case with these themes, though -- it's unfortunately not out of the ordinary to attempt to collect unreasonable charges either coincidentally or as the foundational pillar of a shady business plan. – tripleee Dec 17 '19 at 8:07
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    Thanks for the clarification! That said, charging a reasonable fee is unproblematic, but expecting people not to modify code that they completely have a right to modify is problematic. If a software service with an infrastructural expense is involved (and I'm not convinced it is, as Wordpress themes usually don't qualify) the normal, and much more acceptable, solution, is to give individual tokens (eg username/password) to people who are paying, and they thus identify themselves as paid-up to the network service. – MadHatter Dec 17 '19 at 8:10

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