Due to Revan has been released in Star Wars: Galaxy of Heroes, the devs over at Bioware Austine has made the two SWTOR expansions, Shadow of Revan and Rise of Hutt Cartel, free until Nov 1. So if you havent yet tried them, now is your chance!
Source: N4G PC SWTOR Shadow of Revan and Rise of Hutt is now free to play Until Nov 1