Ditto. Maybe this a common/normal thing? I've had the same experience(s)...especially the memory part. I can put the necessary time into learning a piece so that I'm pretty happy with it ...play it numerous times for couple of weeks ... then a couple weeks later I try to play it and it's like starting over. ugh. I admit I am very tab-dependent and have a pretty lazy/weak ear and a rather undisciplined practice regimen. Plus I was the classic stoner in the 70's and I'm pretty sure I have a brain cell graveyard in my head. hmmmm... I think I just answered my own query.

Good Luck - Take Care