Purchase Code provided by Envato company if theme was purchased via Themeforest.net portal allows you to use automatic updates too.
How to update old themes released before May 2015
Most common issue with themes purchased from Themeforest
What to do in case of unsuccessful demo content import
Demo content includes only demo images
Learn how to debug the most common issues.
What would you do if WordPress ask you “Are you sure you want to do this?” right after click on theme Install button?