NeoOffice pay version vs free version
From their website:


  NeoOffice 2014.1 Free Edition has the same features as NeoOffice in Apple's Mac App Store.
  The only difference is that NeoOffice 2014.1 Free Edition cannot save documents.


The open source license that is used for the NeoOffice source code (GPL) doesn't require that the software be provided for free. It just requires that the source code be made available for free. NeoOffice do offer their source free, but it obviously requires a certain amount of skill and time to compile.