Even when you think you'll remember, there's a darn good chance you'll get your crystal specimens home and think, "Now what the heck was this again?" That's why I like to snap a photo of the crystal with its name/description on my phone while I'm in the store. Then, I keep a file of crystal photos organized by color on my computer, and whenever I want to remember what something, I can look it up quickly.
Try this. Trust me - it'll help you remember what you bought, and if the store has good descriptions of crystals, it will also help you remember its properties.