43 CFR § 3602.28
What records must I maintain and how long must I keep them?
June 11, 2020
(a) BLM may require you to maintain and preserve for 6 years records, maps, and surveys relating to production verification and valuation. These include, but are not limited to, detailed records of quantity, types, and value of commodities you moved, processed, sold, delivered, or used.
(b) You must make such records available to BLM to allow us to determine whether you have complied with statutes, regulations, and the terms of the contract.