As of August 1st, 2013, the free version of Gnaural for Android is no longer a feature-disabled demo, it has all the functionality of the pay version, just perhaps not updated as frequently. The decision was made to give it away because the

Gnaural is a computer-based audio synthesizer capable of generating binaural beats, isochronic tones, pink noise, and many varieties of simulated nature sounds (including rain, waterfall, ocean waves, babbling brook, and wind). Gnaural is i