I summarize this to make sure that I (and potential other readers) understand everything correctly :
- Code plugins using dynamically (or statically) linked LGPL libraries are not allowed to be sold/published on the Unreal Marketplace (according to Unreal Marketplace Guidelines 2.2.f). It’s not important if the LGPL library is distributed together with the plugin on the Unreal Marketplace or provided via an external source/website. The important point here is that the plugin uses a third party software licensed under LGPL and would be sold via the Unreal Marketplace.
- However, if such a plugin (using a dynamically linked LGPL library) is not sold via the Unreal Marketplace but via an external Marketplace (or seller’s own website) then it is allowed to use such a plugin together with the Unreal Engine for buyers or users of the plugin (which uses a dynamically linked LGPL lib.) - according to Unreal EULA (B) (ii), Non-Compatible Licenses.
- The same rules would not only apply to plugins, but also to games & applications (“products”) using both Unreal engine and a dynamically linked external library licensed under LGPL.
If I did not understand that correctly, I would be happy about a short final comment. Thanks 