Qt6 topics merged with General

Tricky commercial licensing questions

  • I've read the FAQ and still have some questions about Qt's commercial license. Would be great if someone could answer on these. I'm considering Linux platform only:

    1. Imagine I bought a commercial license. Does this mean that I must distribute Qt with my app? On Linux application usually distribute is a packages that just contain a references in Qt in official repository. I've checked license of mine at /usr/share/doc/libqt5core5a/copyright - it's non-commercial. So my app will use LGPL Qt after deployment and must comply with LGPL or I have to provide a commercial copy of Qt in package with it. Is it so?

    2. Let's imagine that I develop a library that uses opensource dynamically-linked Qt and sell it (LGPL doesn't forbid this) to company that develops a Qt based GUI application. This company has Commercial license. Providing both Qts are binary compatible could they just replace my LGPL framework with their commercial one? Or they still have to comply LGPL as my library own license comply with it?
      Can I resolve this with some statements in my libraries' license by loosing its terms in case it's used with Commercial and not LGPL copy of Qt framework?

    3. Afaik commercial license is individual, so it's granted to a person, not a working place. What if I fire such person before his license ends? Or I have to buy a new one for his replacement? Is he keeping his license when change employee and may work on products requiring commercial license there?

  • Lifetime Qt Champion


    You should contact the Qt Company directly for that kind of questions. This is a community driven forum.

  • I've forwarded them these questions. Not sure if they'll bother answering to a theoretical questions of a non-customer. Would be better if they could just publicly share Qt Commercial License somewhere.

    Btw, I've google out 10-years old copy of its text leaked to some forum. Its version is 3.2 and Qt is still maintained by Throlltech, so it's obviously isn't valid any more.

    But there are clauses that could answer my question #3.

    1. Trolltech grants to Licensee a non-exclusive, non-transferable,
      perpetual license to make, use and modify copies of the Licensed
      Software for the maximum number of named individuals within Licensee's
      organization ("Named User"(s)) specified in the License Certificate for
      the sole purposes of designing, developing, and testing Licensee's
      software product(s), which may include the Licensed Software
      ("Applications"). Modified Licensed Software shall be considered as
      Licensed Software for the purposes of this Agreement.
    1. Licensee may install copies of the Licensed Software on an unlimited
      number of computers
      provided that only the Named Users use the Licensed
      Software. Licensee may at any time designate another Named User within
      Licensee's organization to replace a then-current Named User by
      notifying Trolltech
      , provided that a) the then-current Named User has
      not been designated as a replacement during the last six (6) months; and
      b) there is no more than the specified number of Named Users at any
      given time.

    I think it's feasible to assume that Qt Company uses something like that too.

  • Moderators

    @truf , the text of the current terms and conditions for a commercial license are actually freely available: https://www.qt.io/terms-conditions/ . So no need to dig up stuff from Trolltech times ;)

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