You can make your WordPress site users to login from only single device at one time. This not only increases the security of your WordPress site but you can stop your users from sharing their login credentials with others especially if you are running a paid membership website.
You might have noticed on various popular websites showing their email subscription box at the end of their blog post’s content. Jetpack by WordPress.Com plugin provides you an email superscription widget but by default there are no options to display it else where. This tutorial explains you how you can easily display Jetpack Subscriptions box after your blog posts.