Your access key gives you access to bug fix updates and major point release feature updates. Activating your access key on a WordPress/Shopp installation provides easy updates in your WordPress admin.
The WordPress Plugins screen in the admin will notify you when a Shopp update is available. When a valid access key is activated on the site, you can run the update with just a couple of clicks. Any officially supported purchased add-ons from shopplugin.net will automatically be updated with core plugin updates.