Yes, there is a history of how many you've used and when, and even the listing numbers you used them on. 

Down the bottom of All Selling where it shows how many you've used of your current allocation there's a small link that I think says history.  If you click on that it shows you when prior freebies were and how many of them you used and how many were left unused.  You can click on the number used and it'll give you the item numbers of the listings you did with those freebies, or that's how I remember it.  I've never had to use it but I did click on it a while back and sent an email about it to a friend.  It would help you argue your case for every one of your listings that you shouldn't have paid for.