Code derived from GPL -licensed code (eg. WordPress plugins) can legally be sold, but the product must also hold a GPL license.
In other words, if you sold it, you grant purchasers the right to redistribute (for free or otherwise) your plugin. That would interfere with ThemeForest’s ‘Single Use’ license, so I don’t think they’ll be accepted.
Yes, that makes sense now danharper.
Hey guys. To be honest, we actually considered selling WordPress plugins for a short time. The rule is that the item must be sold with the general public license. Technically, this means that the purchaser could then redistribute the code for free. However – as I understand it – we wouldn’t be in violation if we chose to charge a fee for each sale.
With that said, we determined that it wasn’t a proper path to take on ThemeForest.