I have a similar problem than this: http://sourceforge.net/p/tcpdf/discussion/435311/thread/32a59ca0/ Developer answered to ask a lawyer but it costs money… a lot?
I only use TCPDF, I have not edited it. Software takes input from users and makes PDF files based on that. It will be used commercially as a service so user will have an account and code will be on my server.
So the question is, can I use TCPDF commercial – I think I can since it is LGPL v3 licensed and these couple of sites like choosealicense and tldrlegal said I can.
So is there anyone who knows and understands this law text.
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Of course you can use LGPL-licensed libraries, but you have to fulfil the requirements stated in the license.
First of all, you are not required to do anything unless you choose to convey/distribute the library or an application that is “linked” to the library (see also §2 of the GPL v3). Since your application resides on your server, you are not distributing the library or an application that depends on this library to your users. Therefore, you may use it as you please, without any restrictions or requirements.
Things change if you want to distribute your server code (e.g. sell it) – see §4 of the LGPL v3 for details. Your code may still be closed-source legally, but users must be able to swap out and modify the LGPL-licensed library. This is typically no problem with normal PHP code, since users could simply edit the .php files of the library. Also, you need to acknowledge your use of the library in the same place where you would state your copyright and license for your code (e.g. a LICENSE or README file in a tarball).