If you have a copy of Blocs V4, you can expand Blocs to Blocs Plus right inside the main Blocs application.
To upgrade Blocs V4 to Blocs V4 Plus, navigate to the main menu and select Help > Upgrade To Blocs Plus. A checkout popup will open and walk you through the process to purchase the Blocs V4 Plus expansion.
Once the in-app purchase is complete, Blocs will activate the Blocs Plus functionality automatically. You can find out more about Blocs plus here.