N.Y. Comp. Codes R. & Regs. tit. 16, § 400.5 – Meter records.

(a) For all steam meters installed on customers' premises records shall be maintained which identify the year purchased, the manufacturer, the type, the identifying number, the nameplate data relative to the rating of the meter, the location, and the date of last test. Such records shall be sufficient to identify all associated meters and accessory equipment affecting the accuracy of the billing.
(b) The test record of each meter and meter device installed on customers' premises shall be retained until a superseding test is made, but for a period of not less than two years.