So, it took me about 15 minutes to realize that the WordPress Shopp plugin actually REMOVED the support key entry field as of version 1.3. Now, when you upgrade to the latest version of Shopp, you have to download a plugin that contains your custom support key. Then, you upload that plugin to the WordPress site where you’ve got Shopp installed in order to “activate” your support key. It’d be more intuitive if they called it a “Shopp support key plugin,” since it really is a plugin – not just a key. After you’ve paid for your updated support key, you can download the support key plugin on your Shopp downloads page, which should be here: https://shopplugin.net/store/account/?downloads. Shopp maintains more information here.