When a render comes back it sits in Studio, above the composer, until you decide what to do with it. That list is your drafts: renders still going, renders that finished, and renders that failed. A finished one is already paid for, so there's no rush. Press Save and it moves to your Library. Renders from a Series skip Studio; they stay on the Series page and join your Library when they finish.
Your Library holds everything you've saved. Finished videos are under Library → Generations, ready to publish or download. The parts are saved too: Library → Tracks for the music, Library → Images for thumbnails and stills, and Library → Videos for the motion loop from a saved Plus video.
You can use any of them again. Type @ while you're writing a new brief and attach up to 8 saved assets. An image sets the opening frame and a video seeds the motion. A track works differently: it passes on the style, not the audio, so the new music is written from scratch and uses usage like any other render.
Deleting something from your Library only removes it from Chillframe. A video you've already put on YouTube stays on YouTube. Two things won't delete at all: a video you've published, and one that's still generating or uploading, which you can cancel or wait out.
If something you saved isn't showing up in your Library, email [email protected] and a human will read it.