That's a good question.
I tried to formulate a position on this matter and it became quite convoluted, so I've decided to take this stance:
For ALL projects released under the GPL or LGPL (any version) PECompact may freely be used, even if the software is a commercial product that consumers pay money for. Since these projects are open source, I'll recognize that contribution to the greater good and reward it with free PECompact use. That said, I still encourage GPL/LGPL developers to buy a shareware license, or commerical license if they can afford it -- but only as a gesture of support for PECompact, not because they are required to.
Any company using this exclusion, then found violating the GPL/LGPL by not distributing their whole and current source, will be required to buy a PECompact license.
I will make mention of this on the licensing page. Other open source licenses this will apply to as well.