I unfortunately didn't retain much in the way of speaking and writing in French, however I can still read it pretty well. I learned it in school, two years in high school and three in college. If anyone is looking to retain the knowledge after a class of some sort though, I recommend keeping your text book for reference, watching movies/tv shows in the language, writing and/or speaking a bit even if it's just on your own, and reading it in some way (books, games, etc). I keep my reading caught up pretty well since I have two Pokemon games (Silver and Sapphire) in French. I know them very well in English so it's helped me read the language better as I play, actually.