There is an interesting read from the NSSF about retaining a copy of the FFL
http://nssf.org/retailers/posts/WAN-Time-to-Retain-Copies-Federal-Firearms-Licenses.cfm"
Though many retailers tell our consultants they believe they must retain these copies indefinitely, just as often our consultants are asked, "Just how long do I have to retain these FFL copies?"The answer may be surprising:
A retailer does not have to retain them at all! The section of ATF regulations that govern the providing of FFL copies is 27 CFR 478.94. In pertinent part, this regulation states:
"A licensed importer, licensed manufacturer, or licensed dealer selling or otherwise disposing of firearms, and a licensed collector selling or otherwise disposing of curios or relics, to another licensee shall verify the identity and licensed status of the transferee prior to making the transaction. Verification shall be established by the transferee furnishing to the transferor a certified copy of the transferee's license and by such other means as the transferor deems necessary: Provided, That it shall not be required (a) for a transferee who has furnished a certified copy of its license to a transferor to again furnish such certified copy to that transferor during the term of the transferee's current license … ."
The fact that another copy need not be furnished during the term of the current license implies that the first copy is retained;
however, there is nothing in this section that explicitly requires the retention of the first FFL copy. Further, ATF regulation 27 CFR 478.129, which provides guidance on the retention of firearms records and forms, makes no mention about the retention of FFL copies. 
