unlock article after sign up + cllecting data about user

Hello, only joomla expert bid ... I need to insert simple sign-up form (pop-up box) with sign up buttons (email+password) when somebody want to read whole article... After registration/login he can read whole article. Articles are created in SP page builder in joomla. Sign up user can read all articles on web page - after they unlocked... Users should be written to database and easy export in csv from joomla. Also I need that it is written to database from what article (article link) user was sign up/login. There should be also possible to login/logout.