There is no specified period of retention in the SQF Code.
From the SQF Code:
2.2.2 Records (M)
188.8.131.52 Records shall be readily accessible, retrievable, securely stored to prevent damage and deterioration and shall be retained in accordance with periods specified by a customer or regulations.
From SQF Guidance:
There is no prescribed duration for retention of records. For some suppliers it may be prescribed by legislation, customer requirements or insurance coverage. Apart from those requirements, the general rule is to retain records for the commercial shelf-life of the product (i.e., the maximum time before consumption). However for short shelf-life products, suppliers must retain records beyond the next recertification audit, as a minimum.
So retaining documents for 1 year complies with the SQF Code (as long as you retain until your next recertification audit). I do see a customer requirement for packaging records to be retained for the life of the finished product now and then so I would also get agreement from your customers that this is acceptable.