restricting contnet

I’m not sure if I’m in the right place to ask this but after looking for weeks perhaps someone here will be able to help point me in the right direction.

I’m after a something that will pop up once two posts have been read. To continue free reading, visitors must subscribe (for free).

I want this to kick into action from one page only.
This page lists features. I want to allow subscription-free reading of two features from this page during any given month. Thereafter, people need to sign up.

Anyone know of anything like that? I’m not having much luck but perhaps have been searching for the wrong thing: I have tried: protect content, enforce membership, registration pop up. None of those search terms helped me find what i am looking for.

Thanks for any pointers!

https://ww.wp.xz.cn/plugins/simplr-registration-form/