From their site: This API is available to anyone who wishes to use our database for their own music project, website or program. If you currently use the web to search out lyrics or use code tricks to access other lyrics websites to display relevant lyrics text for your content you can now have a reliable source without the hassle.
Click the "Track this API" button on any profile page and never miss an API update, new app, or breaking news for that API again.
Where and how do I get my API key and the documentation?
This is an official and illegal API, Lyrics are covered by copyright.