Pay-for-play is not a new concept in the streaming world. In the early internet radio days, would-be Pandora competitors Jango and Last.fm offered bands guaranteed plays in exchange for cash. Unofficial payola on Spotify has persisted for years: Independent playlisters accept money in return for placement of songs. But Discovery Mode is the first time Spotify has officially embraced pay-for-play, with the algorithmic aspect of the tool further complicating things.
Source: Could Spotify’s New Discovery Mode Be Considered Payola?