Adding "to read the rest of this post you need to be a subscriber" to blog posts?

Hello there, I have a business news website and the articles I would like free users to be able to read up to a certain point but if you want to read all the article you need to either be a customer already and log into your account or subscribe (for a small monthly fee) to be a full subscriber and then when you are logged in you can read all the content

Very similar to what newspapers have such as WSJ and NYT when you can read the first paragraph but after that you need to log in (and be a paid subscriber)

i cannot see if this is possible ? SS has passwords for pages etc but no option to add a block within a blog post that would create such as pop up or overlay box. 

could anyone advise? 

thank you in advance