N.Y. Comp. Codes R. & Regs. tit. 19, § 190.3 – Records to be maintained.

(a) duplicate signed copies of all contracts;
(b) copies of notices to the Department of State pursuant to section 190.4 of this Part;
(c) copies of landlord's authorization for each apartment to which prospective tenants are referred; and
(d) duplicate signed copies of escrow agreements.

The following records of every business transaction must be maintained at the principal office of the vendor for a period of three years: