I haven't taken quite that much time off at once, but when I first moved away and started going to college, it would be anywhere from 3 to 6 months between times I was able to ride. I never noticed that I forgot
anything, but I would tire easily and get sore quickly. My seat would be a little worse than it was before but it usually came back quickly. LOL, my Dad calls it "suffering from a case of basketball-butt" because your butt is bouncing all over the place
It's similar to riding a bike. You never really forget but sometimes it can take a while for all the gears to start working in sync again.