Hello Friends, I am new here. My first question is: How do I provide content to free subscribers but insert a Read More widget so people must subscribe to continue reading my article? or
I want to provide excerpts from every article, post, and video description, then activate the method described above. Thank you guys
Use conditionals (I like shortcodes). 
Yeah, conditionals would be the easy way. See: https://s2member.com/kb-article/s2if-simple-shortcode-conditionals/
Another option is writing a customization (e.g. must-use plugin, functions.php) that uses WP’s existing Read More feature, then protect the post/page with s2, but in the lists of posts/pages shows the preview snippet up to the read-more tag/block.
Thanks guys, I have to figure out how to do it