If you are using a child theme e.g. BlogVi or BlogMate these are the child themes of Bloglo . So In order to upgrade you need to purchase parent theme that is Bloglo Pro. In order to import demos that theme has to offers you need to install and activate Hester Core plugin, after activating the plugin you can import any demo you like whether it’s BlogVi demo or BlogMate demo or any other demo  from Demo Library.