You can use this plugin in your website to add list of serial numbers and guarantee (optional) for your products in the dashboard and after that user can check his/her product if it is orginal or not.

Add-on for Contact Form 7 plugin. Add your own mail-tag to display the serial number.

The easiest way to sell digital products and manage licenses with WooCommerce.

A discrete plugin to add counter/time/timestamp to mails received with shortcodes that can be added anywhere on your mail