If your track is a cover version of a song/lyric for which you are not the author you need obtain consent from the author(s) to use it, otherwise legal actions can be taken against you. There are services out there that make this process easy for you. One service for example is our partnership with Easy Song Licensing.
As per our agreement, each and every label is responsible for ensuring that the content they distribute is legally cleared to be distributed. Websites that sell samples, such as SoundsToSample.com, Loopmasters.com, etc., all grant consumers the ability to make music off the samples sold and grant permission to sell these recordings. We recommend that you purchase sample packs off those websites if ever interested in sampling.