Online stores—such as our website and Amazon—will email you a confirmation with your order details. That email will include the date of purchase, order number, etc.
You can also go back to the site you purchased your item from, then find your order history. The order number may look different depending on which retailer you purchased your product from.
Here are some examples:
Bed, Bath, & Beyond: BBBxxxxxxxxxx
Best Buy: BBY01-xxxxxxxxxxxx
If you are still unsure, you can always take a screenshot of any information you do have and email our helpful support team for assistance.