I know that all products in codecanyon must be opensource. This mean who buy my code can use my code for their product. For example, if I create addon for Visual Composer, they can get it and use that on their new version. How can I survive in this case on envato market? This is the reason why I am still have no product for sell. I understand that this problem has no solution.
Nobody can use your product to create another product to sell here on Envato without your permission. Seriously, if it was that bad as you describing it, why would anybody uploaded product here? Do you think that all those thousand of Envato authors are uploading items here just for charitable reason or what?
Yes they can, if the product is licensed as GPL.
Not true, though GPL would allow them to re-sell, re-dustribute elsewhere, Envato still has the right to control authors work when uploaded to their network, in such a case the original author can work with Envato to remove the clone regardless of GPL.
Nop, there is also the 9 changes - copyright rule, that envato has to accept, based on GPL / Court rights. An author can actually hunt that done, if the work coming from a plugin / theme is enough to be an " advanced system based on a previous framework ".
Framework can be any type of software that has been used as starter kit.