Purchase License After or Before?



  • Hi,

    I'm planning to use Qt for an application which is still in development. However I have not decided yet whether it's going to be commercial or open/closed source, as all this will depend on several factors and the success of the software. In case I decided to make it commercial, can I buy a Qt license after development finished?

    Thanks.


  • Moderators

    Hi @qtoptus,

    See https://forum.qt.io/topic/61625/qt-commercial-license-terms-independent-developers to get a feel for how it works.

    I'm not affiliated with the Qt Company and I'm not a lawyer, but I understand that if you wish to release your software under the commercial Qt license, then you should hold a valid commercial license throughout your development process.

    Having said that, note that you can release your software under a LGPL license while keeping it closed-source. You just need to make sure that you don't use any non-LGPL modules (for example, Qt Charts) and comply with the LGPL requirements.



  • @JKSH Thanks for your reply. My concern is when should I buy the license, before development starts, or can it be obtained anytime just before releasing the software?


  • Moderators

    @qtoptus said in Purchase License After or Before?:

    @JKSH Thanks for your reply. My concern is when should I buy the license, before development starts, or can it be obtained anytime just before releasing the software?

    See the link I posted above: https://forum.qt.io/topic/61625/qt-commercial-license-terms-independent-developers Pay particular attention to @tekojo's comments.

    (I hesitate to give you a black-and-white answer because I don't use the commercial license myself, and I don't speak for the Qt Company)



  • @JKSH

    Yeah I read the thread mentioned. They actually leave developers with uncertainty so they have to buy the license from the very beginning of development to avoid any licensing "legal" hassles.
    Unfortunately the license type pricing scheme and the nature of my project make it unrealistic for me to get an early license. Abstracting the core project from GUI is not something easy, or that GUI integration can be done in a couple of months.
    I will look for an alternative toolkit.


  • Moderators

    @qtoptus said in Purchase License After or Before?:

    Yeah I read the thread mentioned. They actually leave developers with uncertainty so they have to buy the license from the very beginning of development to avoid any licensing "legal" hassles.

    I don't think it's designed to be nasty and uncertain like that. It's just the terms of the license: If you want to use the commercial license, then you pay for the license when you start developing. I think it's a bit like renting an apartment: You pay from the time you start using the apartment, until the time you leave the apartment.

    Unfortunately the license type pricing scheme and the nature of my project make it unrealistic for me to get an early license. Abstracting the core project from GUI is not something easy, or that GUI integration can be done in a couple of months.
    I will look for an alternative toolkit.

    Is the free LGPL license a viable option for your project? The LGPL is compatible with commercial, closed-source applications.

    Anyway, regardless of which direction you take, all the best with your project.



  • @JKSH Thanks.
    This is the problem I cannot decide on the license type before the project is completed and ready for release. I may decide earlier during development but all depends on how it goes...
    I would buy a license if I was able to guarantee finishing the project in a defined time frame.
    Here's one scenario, I decided to get a license and then spent 1 to 2 years on development. For some circumstances I decided to drop the project, or hold on for some time!
    However a perpetual license would be more flexible and reasonable to think of insuch situations. The whole idea of monthly subscription license is just nonsense unless we pay for a service or support.



  • After reading the FAQ about commercial license (# 2.13) answers my question. Fair enough! However Lets say I started developing my project and using some other GUI toolkit, and made closed-source commercial releases. Later on the team decided on switching to Qt because all its advantages, can I buy Qt commercial license to start porting the application to the new GUI?



  • By your description you do not even need to purchase the license when you start the porting. You can start the development as a LGPL user and purchase the license only if, during the process, you realise you need to exceed the boudaries of LGPL



  • This is not legal (or any other kind of) advice. But if I were running a company which would offer a software library with similar licencing option, I wouldn't mind if people would do in-house development first with the open source library code/binary and after deciding to release with commercial option would pay for the whole development time, being honest and paying afterwards the whole sum.

    According to GNU foundation in-house development and even in-house use is not the same as distributing the software, it's personal/private use (https://www.gnu.org/licenses/gpl-faq.html#InternalDistribution). I don't know how Qt company would interpret this. Probably this has not been tried in court. But in any case nobody can sue you for doing development with open source Qt without paying (you can always say you were going to publish it as open source). As tekojo said in the other thread, it's more about honesty and good ethics than legal matter. In my opinion, if you paid the whole sum after your decision it would be both legal and ethical.

    Also, as was already mentioned, be sure you understand that you can keep you own code closed and commercial even if you publish the program with open source Qt, if you link dynamically and don't use the more restrictively licenced libraries.


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