[orlandohill]

Both the PolyForm Noncommercial License and the Prosperity Public License are irrevocable. There is no lock-in. Everyone gets the code, just like with an OSI-approved "open source" license.

Dual commercial/non-commercial licensing like this is a simple way to require commercial users to fund the further development and maintenance of the software.

[cornholio]

They are irrevocable, but they also disallow commercial redistribution of modified copies - in perpetuity.

This means that when the original vendor changes new versions of the software to a draconic proprietary license (as is their right as the full owner of the copyright), the community can't fork an older version and keep it up to date and distribute that; they can just use older versions until they become obsolete, incompatible, accumulate security holes etc. They are locked in to the vendor is they need those same features going forward.

[orlandohill]

The commercial license typically grants the right to sublicense the software as part of a larger piece of software that can be sold commercially.

Both commercial and non-commercial users can copy, modify, and redistribute modified and unmodified copies. Again, there is no lock-in.

There's little incentive for the developers to switch from dual commercial/non-commercial licensing of the source code to only distributing compiled executables. The whole point of choosing the dual licensing model is that it's more attractive to customers. You wouldn't want to use such a model if you were trying to keep trade secrets, but in such a case you wouldn't consider using an open source license either.

Further reading:

https://duallicensing.com/ https://indieopensource.com/public-private/indies

[cornholio]

> Both commercial and non-commercial users can copy, modify, and redistribute modified and unmodified copies.

I don't follow. Both examples you provided explicitly forbid commercial redistribution:

  The Prosperity Public License 3.0.0
  license allows you to use *and share this software for noncommercial purposes for free* and to try this software for commercial purposes for thirty days
  [no other distribution allowances are made in the rest of the license]


  PolyForm Noncommercial License 1.0.0
  Your license to distribute covers distributing the software with changes and new works permitted by *Changes and New Works License*.
  Changes and New Works License: The licensor grants you an additional copyright license to make changes and new works based on the software *for any permitted purpose*.
  [Complete list of permitted purposes]
  "Any noncommercial purpose" ; "Personal use ... without any anticipated commercial application"; "Noncommercial Organizations"

So both licenses disallow distribution if done for a commercial purpose. Do you mean to say that you can dual license, under such a non-commercial license and also under an open license, that allows commercial distribution? But then, how would you discourage commercial users from simply downloading and using the open source version? We're back to the service model of financing open source.

[orlandohill]

Those are examples of non-commercial licenses, licenses that grant rights, free of charge, but restrict commercial use of software.

When I say dual licensing, I am referring to the business model of offering software for free under a non-commercial license, and charging for commercial usage rights. Kyle E. Mitchell calls this Free-and-Paid Dual Licensing.

https://writing.kemitchell.com/2023/09/10/Two-Kinds-Dual-Lic...

To use such a business model you also need a commercial license. There's no one-size-fits-all solution, and it's normally something that requires input from a legal professional. Kyle has made a couple of recent efforts to improve things.

https://fastpathlicense.com/ https://commercial.polyformproject.org/