SESAC, ASCAP, and BMI are three separate and distinct Performing Rights Organizations (PRO). Each organization represents different copyright holders (songwriters, composers, and publishers) and licenses only the copyrighted works of its own respective copyright holders. Licenses with ASCAP and BMI DO NOT grant you authorization to use the copyrighted music of SESAC-represented songwriters, composers or publishers.
Since a license with ASCAP and/or BMI does not grant authorization to publicly perform songs in the SESAC repertory, most businesses obtain licenses with all three in order to have proper copyright clearance for virtually all of the copyrighted music in the world.