Physical, in-person, monthly examinations by an independent auditing/accounting firm ensures that for every LD2 token issued, exactly one ounce of .999 fine physical silver is on deposit at the depository. The auditor also verifies that the total number of burned tokens equals the number of ounces shipped by the depository during token redemptions.
In addition to the examination reports the auditor and depository both independently update the smart contract. Each monthly examination report, beginning in May 2018, is available as a PDF below.