To get a premium extension you must purchase it in the store first.
You can download the purchased extension from many sources:
From the Purchase Confirmation screen
From the Purchase Receipt email
From your BracketSpace account Dashboard
To install the extension plugin please navigate in your WordPress Dashboard to
Add New. Then click the Upload Plugin button.
Select the package you downloaded and click
Install Now button.
Why it's important to activate the extension? Because this way you'll get the plugin updates directly in your WordPress.
To activate the plugin simply go to
Extensions and in the extension box provide your license key.
Then just click the
Save and activate license button.
Free extesions are available in the WordPress.org repository and you can install them via your wp-admin. No specific activation is required, the extension will act as a regular plugin.