I'm programming a PHP script and i want it so its free to use a branded version of the script but you must specifically buy a unbranded version if you want to remove the Powered by xyz in the footer. how could i do this from a licensing point of view ie so its illegal to remove the branding from the free version. Would i have to write my own EULA or could i just use a GNU licence? also in the script i have use a portion of a different script released under GNU GPL and correctly given full credit to the author could i still use this code?
I don't think you can incorporate someone else's GPL code and then add additional licencing requirements to your own version.
This is actually one of my beefs with Open Source licensing: There's no correct answer for this. I started out using phpNuke and that designer had in place a restriction that you had to leave in a link back to the phpNuke site, have it publicly visible on all outputted pages, and had proof from the FSF concerning his requirement. That's discussed here in the FAQ: http://www.gnu.org/licenses/gpl-faq.html#IWantCredit But yet other Open Source developers state there's no legal requirement for having the output contain the licensing and link back. I would just state that the "Powered by xyz" is a requirement as credit much be given. You'll get naysayers. Just point them at phpNuke and how others do it that way. Then we have the developers who feel that GPL has to be applied to everybody but themselves and they're allowed to do whatever they want with no credit or anything. Those folks really suck. To be honest, I don't release any of my code anymore. It's not worth the trouble. It depends on how the code is inserted into the overall program. Without knowing this, it;s hard to say. If it's a copy and paste directly into the code, looks like the final product has to be GPL'ed. If it's like a plugin or module that sits outside of the main code, looks like you can get away with it. All this makes my head spin.
awesome thanks for the reply and yeah i know why is it so much effort to give something out for free well i have 3 things jQuery & FCKeditor which are both just external javascript things. and a class from phpBB which I've edited heavily to work with my script.
In all honesty, go read through the GPL link I gave up there and see if it makes sense to you. I can see the jQuery and FCKeditor but the class may be a problem. Heck, drop them an email and ask. That's what they're there for. Just try your best t give as much information as possible when you send off your email.
Prior to the new GPL, the answer to this was pretty simple. If the module/library is LGPL = yes, you can redistribute it with different terms from the oveall product. If the module/library is GPL = no, you must keep the GPL license for your entire product. I think the new version of GPL made some changes to this but I've been too lazy to look deeply into it. I don't think the new version is that popular anyway.