I don't think I think when I play. I have a photographic memory for chords, and when I'm playing, the right chords appear in my mind like photographs long before I get to them.
I know every note in every song, the whole history of it, even parts that were there and are gone.
I am very good at remembering music and am absolutely certain that I never heard 'Taurus' until 2014.
You obviously don't really forget how to play the old songs; you just don't have to spend so much time convincing yourself that you remember them. Way less mental energy is spent swimming around in lyrics you've already written and chords you've already played.
I have never been able to remember the number of my driver's license, and there have been times when I couldn't even remember my own telephone number, but when I hear a song, sometimes only once, I never forget the melody or the lyric.
I used to memorize music when I was real young. Schoolwork, not so much. But music I could remember.
It's incredibly important to me that you remember a song right after the first or second time you hear it. That something sticks to you, something that makes you feel, 'I need to hear that song again.' That's fundamental. Something you want again. And again.
You know, your ears record. You might can sing a song once you hear it.