How to put a DJ mix of songs on youtube, without the sound being taken off.?

whenever i try to put a mix on youtube that i made, they take the sound off because i didnt buy them or something. i need some help on being able to put a mix on youtube without them taking it off. i know i have to have that thing under the video that has the song and where you can buy it, but how do i do that when its a mix instead of just one song?