Hi: I downloaded audacity 6 months ago and I attempted to remove lead vocals out of an mp3 file, your software did remove vocals but highly distorted the rest of the music and I assumed this was to prevent me from using the editted track without purchasing the software. Obviously this is not the case if audacity is free. Thak you for your prompt attention to this matter.
That is correct, Audacity is free, open source software.
Unfortunately vocal removal will only work well if the vocal is in the exact middle of the stereo spread, and all other sounds are toward the left or right, and there is no stereo effect on the vocal, and the audio that you are working with is a good quality recording and not an MP3 or other compressed format. Without these conditions being met the result is likely to be disappointing. See these links for more information:
http://manual.audacityteam.org/o/man/vocal_remover.html
http://manual.audacityteam.org/o/man/tutorial_vocal_removal_and_isolation.html