'How to add user whitelisting

I have a subdomain of my website that I need to whitelist specific users/computers that have paid for the service. Without using a login system, ip banning, or cookies.

In previous attempts I tried using fingerprintjs but I had trouble adding that function. I can modify and change all components of the website if that helps, and I use cloudflare.



Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source