This may not be an issue for you but I have always had a horrible sleep schedule and I found that when I tried hard to consistently get a good amount of sleep each night, my memory and concentration improved. Also, meditation personally helps me a lot but I know it doesn't work for everyone

With memory, I've heard doing puzzle games or doing a daily vocabulary (checking in on dictionary dot com) helps!

Mindfulness and lists! The second I remember that I need to do something, I either do it immediately or write it straight down where I know I'll see it again soon. It took me a long time to get in the habit of not procrastinating, but it's helped me a ton. That and setting timers for tasks cause I tend to be "time blind" and forget that I need to be somewhere sooner than I think I do...