Leasing rights give the music artist a certain amount of uses per lease. Once it runs out, the customer would need to buy another lease for the same beat. You can give out as many units as you can, it's really all up to you.
Another thing about leasing is that the producer can sell the beat to multiple artists, as long as nobody buys the exclusive rights to it..
We use samples in some of our beats. All of them are royalty free samples. This means that you don’t have to clear them before you use them on your album/mixtape. If you would like to know if a beat conatins samples you can contact us anytime at firstname.lastname@example.org