В readme перечислено:
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О разработчиках
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+ Модули AIMP2 (c) 2006-2007 Команда AIMP (http://www.aimp.ru)
+ Библиотека BASS (+ дополнения) (c) 1999-2007 Un4seen Developments (http://www.un4seen.com)
+ Ogg Vorbis (c) 1994-2007 the Xiphophorus Company (http://www.vorbis.com)
+ LAME MP3 Encoder (http://lame.sourceforge.net)
+ Monkey's Audio (c) 2000-2007 Matthew T. Ashland (http://www.monkeysaudio.com)
+ FLAC (c) 2000-2007 Josh Coalson (http://flac.sourceforge.net/)
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Из этого:
LAME - LGPL,
FLAC - часть под BSD license, часть по GPL
Monkey's Audio - не GPL, но можно свободно использовать во freeware.
> FLAC is open to third-party developers who want to add support for FLAC into their programs. All the necessary functionality is contained the libFLAC libraries which are licensed under __Xiph.org's BSD license.__