It is important to remember that many of these songs were without the artist's permission. Lana has expressed frustration in the past regarding her personal demos being accessed illegally. Supporting her official releases and streaming her sanctioned "from the vault" tracks—like those found on Blue Banisters or the official release of "Say Yes to Heaven"—is the best way to ensure the artist is compensated for her work.
Officially, Lana Del Rey has begun releasing vault tracks on her studio albums or as standalone singles: lana del rey unreleased download full