If you're listening to a series of audio (or video!) files like it's an audiobook, I recommend Voice Audiobook Player. In addition to remembering your playback position within one of the files in a folder, it's open source and ad-free, and has options to adjust the playback speed.
I have been used many of them but found this one is the best for me.
It's simply, compact and direct to your job.
the App download link is here.
Haven should meet your requirements (a slightly newer version can be found in my repo. It won't write 24/7 – but listen to its environment 24/7, then write when "anything moves" (motion, sound, vibration & light detection trigger recording). It will record audio and make photos.
The app is available for free at Google Play (first link) and via ...