Once you register in Artbees themes website, your product information along with the date of purchase is recorded in database. You can check the status by logging in Artbees themes website and then visit your Dashboard > Account
Here you can find how many days are remaining from your customer support subscription associated with the products you have registered in Artbees website. You can also see when it will end so you can extend before it expires.
Alternatively, Artbees sends email notifications one week prior your subscription expiration date.