The words 'archive' and 'Spotify' do not go together naturally! (Ditto any subscription service).
From the title I was expecting something like "how I archived my Spotify memories in a plain text file".
It is relatively easy (currently) to take a playlist and back it up as a plain text file.
CTRL+A, CTRL+C from web or desktop puts a newline separated plain text list of songs on your clipboard.
Main risk is that the list is in the format of "https[:]//open[.]spotify[.]com/track/[song-id]", so Spotify may break the lookup of these IDs in the future.
It's still valuable stuff. What I wouldn't give for a text file containing a list of everything I had on my iPod classic circa 2006.
Anna's Archive would disagree.
Fortunately, there is a way to extract song lists - via API, official export, or even MCP. https://github.com/marcelmarais/spotify-mcp-server
I recommend doing so, even as a backup.