See https://doc.qt.io/qt-6/quuid.html

@Joe-von-Habsburg There are, I assume, numerous online product activation services like LicenseSpring (no affiliation or recommendation).

You could roll-your-own with something like Partial Key/Serial Validation or something similar.

@Rahul-Das said in Selling a GPL/LGPL software as a company:

How the end user gets the dependency libs - well - could be through a repository ? or distribution by the you (company) ?
As long as the libs are not changed (which is normally the case - unless you recompile it), what's the problem ?

This has been discussed over and over again: You need to have the source code of the exact version of the LGPL library you used. And it is not sufficient to link to someone else hosting the code. You must have control over the source. You can host it yourself and maybe you could also have your own repository on GITHub or similar.

@Volker75 said in Selling a GPL/LGPL software as a company:

Well, the initial question was about selling GPL (and LGPL) software.

Nothing is preventing you from selling software under the GPL (as long as you also provide the source code, which is not what the OP wants). However, you cannot in any way restrict what the customer does with the software afterwards. He is allowed to sell it, too. He is also allowed to give it away for free. This hardly makes it a viable business strategy. Linux is GPL and SUSE and RedHat are selling Linux. It mostly works for them because of the support they are selling together with the product.

@SGaist said in Can I charge customer to use Software if I have created Software using open source Qt?:

Also, if you do any changes to Qt for one reason or another, you have to publish these changes.

In addition to what @SGaist said: You need to have the source code of the Qt version that you used. You can either provide a written offer valid for at least 3 months for your customer to request the Qt source code (not your own source code). Or you provide the Qt source code in the same way as your software (if your software can be downloaded, place a download link to the Qt source code in the same place). A download link to someone else hosting the same Qt source code does not count. You have to host it in the same place as your software.

Furthermore, the LGPL requires that the user is able to relink with a different Qt version. If you are using Qt's DLLs this is taken care of already as the user can just replace the DLLs.

@JonB said in Qt License Inquiries:

@Braynex said in Qt License Inquiries:

I haven't decided yet whether to use Qt (C++) or PySide (Python).

Just to remind you of one thing. If you choose Python you must adopt the PySide you mention, either PySide2 or the new PySide6. Don't be tempted to pick the better known/more-featured PyQt5 or PyQt6 you will see around the web, because that requires GPL rather than LGPL. No such issue if you go C++.

Hi JonB, noted, thank you for the tips.

Our first choice is PySide6 for this project because PyQt's GPL licensing is out of the picture due to the nature of this project.

Kind regards,
Braynex

@Exotic_Devel, acredito que não seja culpa do open source, por que:

Qt usa duas licenças, a Comercial e a LGPL. A licença LGPL diz que:

o. Em caso de ligação dinâmica, então o teu desenvolvimento (o código que você desenvolver) é "trabalho que usa a biblioteca". Sendo assim, o código que você desenvolver apenas usa as bibliotecas Qt, então seu código pode ser proprietário.

o. Em caso de vinculação estática da biblioteca, o próprio aplicativo é "trabalho que faz parte da biblioteca". Qualquer ligação estática com uma biblioteca LGPL, obriga a fornecer o código-fonte do aplicativo para o usuário sob a LGPL.

Então do meu ponto de vista, se existe um culpado, é a Apple! por não permitir vinculação dinâmica! Hora, bastava permitir que resolveria a questão: Quem estivesse sobre licença comercial, faria o vinculo estático; Quem estivesse utilizando alguma biblioteca open, então faria o vinculo dinâmico.

Não é novidade, isso só reafirma que a Apple não é muito edepta do opensource. :-)

@dldd the old wiki was a CC license, so that should still apply.
Not sure how that works for code snippets though.

I'll have to edit the template to include a note on that.

Solved -> i adde the avcodec_56.dll and other ffmpeg .dll to my .exe folder and that worked.
Thanks a lot for help.

Hi,

@wolfgang959 said:

Can i use the opensource version of Qt Creator under the LGPL to make closed source software and sell it, as long as the Qt libraries are dynamically linked?

I presume you mean the LGPL version of Qt (the libraries), not Qt Creator (the IDE)? The Qt Company is happy with what you have described: http://www.qt.io/faq/

"The LGPL allows you to keep the source code of your application private as long as it is “work that uses” the library. Dynamic linking is usually recommended here."

Note: Nobody really knows the legal answer to this question from a broad LGPL point of view, because this has never been dealt with by the courts before.

If i use MinGW is anything i compile with it then restricted to the GPL

No. The tools are GPL, but your code doesn't have to be GPL.

If i use LLVM (not tried it yet but seems promising), will i have to compile Qt Creator, and the Qt framework with CLang(++) in order to then compile my Qt projects with CLang?

You don't have to compile Qt Creator. You might have to compile Qt... I'm not sure, but I think the GCC version of Qt is compatible with clang.

i can then use the same setup of Qt creator/framework as well as the same compiler, meaning i then don't for instance use MSVC for windows and gcc for linux but can use LLVM for both.

Frankly, this has zero impact on my development workflow. I use MSVC on Windows and GCC on Linux, but my code can be shared between the two machines without any modifications, and the way I use Qt Creator is exactly the same on both machines.

This is the open source forum. When you like to buy a commercial license of Qt Libs you need to contact Digia.

@mehrdad said:

in publish process there is a part that ask licence file (list of numbers)
first, what is the syntax of this file?

That is an Ubuntu-specific requirement, so most users on this forum don't know the answer.

maybe, i also ask this question in stackoverflow
but i think i have better chance to find a qt programmer that published an app in software center.

The Ubuntu SDK is built on on top of Qt, so most Ubuntu app publishers know Qt. Your best chance is to ask at http://askubuntu.com/

Good luck!

You could also release your statically linked application to the app store and put a link in your about text that points to place where interested people can download your object files and a linker script that allows them to link your app as they wish.