While not a permanent MP3 file you can move between devices freely, these services allow you to "download" the track for offline listening within their respective apps:
: You can buy the digital single or the full album in MP3 format. Let Her Go MP3 Download
: Offers the song for purchase and download in various high-quality formats, including MP3. While not a permanent MP3 file you can
: The single is available for purchase on the iTunes Store . Streaming with Offline Access permanent MP3 files
: The track has surpassed one billion streams and is available for offline download with a Premium subscription. Deezer : Provides streaming and offline access.
: Features the Anniversary Edition (with Ed Sheeran) for streaming.
For high-quality, permanent MP3 files, the following platforms are the standard legal options: