i found this on their website,
In order to provide our customer the better warranty service, TP-LINK UK will offer a 3 Year Warranty program on our selected SOHO products*. The prior version of the 2+1 Year warranty policy will be cancelled and no longer valid. In other words, the warranty period will be automatically upgraded to 3 years without requiring you to register products on our website anymore as soon as your SOHO product* is purchased. What’s more, you may receive the same warranty service, technical support and the RMA support as usual. So please retain A COPY OF YOUR INVOICE/RECEIPT to verify the purchase for any future warranty claim
so i think there is no need to register warranty.