How can I Implement this functionality of paid subscription for paid blog posts? [closed]

So, I am making a blog website using HTML, CSS, PHP, MySQL. Now I want to add a functionality to my website with which all the visitors of my website can read certain blogs. But to read all the rest of the blogs they have to signup and subscribe to a 1 month/6 month/12-month plan. After the subscription is confirmed by the admin they can easily read all the blogs on my website. And if anyone is trying to read a certain 'paid' blog then they will get a restriction error'. I have figured out how to add the payment and other stuff but what I am struggling with is how I can block public visitors who aren't signed up from viewing paid content. How can I do that?