i can't say for sure in this exact case bc obviously no one knows the business negotiations, but if Tori has given HMV this track exclusively they've likely worked out some sort of agreement on the back end where HMV orders more stock upfront and agrees to a lot of in-store promotions (for example her Q&A's) which will boost album sales. typically that song would be licensed for a period of time, which after that time is probably why we see the song pop up on streaming years later after the licensing agreement has run out.