I have a 13 yr old dd and a 4 yr old dd homeschooling and yes, I do keep my Sonlight cores. I keep a few other things, but I also sell cirriculum that I am not sure of, or is cheap enough that I can repurchase later if I choose to. I know that the Sonlight cores will change some over time, but they worked great for us now, so they will work just fine later.