They can look up a receipt of you used a credit card, input your email address at checkout, or if it was purchased on a customer agreement. They can also do not-receipted returns as long as a barcode is present; in that case it will go on a store credit that is only usable by the person who makes the return.
If you used CC, they can reference the transaction!
Talk to the employee and they should have a tag number or bar code number for that flooring...
Thanks! Your answer is awaiting moderation.