Email notifications for a product or a product variant are sent once its price drops to (or gets below) the target price set by the customer.
You can update the product price by editing the product using your store admin. The Watchlyst monitors as per the settings saved in The Watchlyst dashboard(Dashboard--settings--monitor).
1. If the monitor is set to Auto, it will automatically monitor price changes every 4 hours to send price drop email notifications to subscribed users.
2. If the monitor is set to Manual, it will monitor prices and send email notifications as soon as the 'Monitor Now' button is clicked.
Note: This is a one time email for the subscribed alert. If you update the prices again no email notifications will be sent to the same customer.