Well bro the way i check them to see they are still good and not used is cause i have a account in my coke rewards and since the limit is 120 each week i always fill it up the same day it goes to zero again ....so once its all filled up i try to put more codes to it and if they work it will tell me to save them up for the next time it resets....and if its used code it will tell me this.... Lets give it another whirl...The code you entered has already been used, so enter a valid code above.....so thats how i check them bro....and i make sure that they will work for other people like you.