I have noticed alot of people, where i train, say that they can never remember the moves and " oh i think this is normal because it takes two years to learn that move etc" but these people you never see them drilling moves. When i say drilling i'm talking about 150 reps minium.
This for me is the way forward. I often ask myself, after analysing my performance in class, why didn't i do that or why didn't i do this. It's because i am doing a technique in class. That the instructor will show two times. Will do it with partner about for 4 minutes. Then will roll. Then next class do something different. So how can i expect to remember something i'm doing or drilling for 5 mins once every two months? I think thats a difficult feat for anybody... The result the guy who starts to spar may try that new technique doesent work and goes back to what he can do best.
My plan for improvement is: say you train three- four times a week. When you get home write the moves down that the instructor tells you and if you can drill them each 150 reps or more. If you can't find a training partner: Do what i do i have a like a giant tiger thing..(well its not mine but my girlfreinds) put the gi around it and drill. It doesent work for every postion but for example it works for lot of chokes because his neck is same size as humans. Or just do it mentally as well.
There comes a time in you training when you say if somethings not working then try something different. If you are happy to just say oh it takes years and i'll never be great, i started too later. Be my guest but from now on im going to drill...drill ..drilll!
by the way i am not asuming you dont drill alot just talking about my experiance. And oviously for a detailed article on drilling muscle memory just look online.