Below is a photo example to help locate this information on your product.
This information can be found stamped directly into the plastic of your product on the very bottom of the pail or just under the lid.
The model number of your diaper pail will begin with a 23. The date of manufacture will typically be noted as a date clock. There will be an arrow pointing to the month of manufacture with the last 2 digits of the year stamped on either side of the arrow.
(locate the section on your diaper pail where "model" is pointing to.)