I’ve just installed the “Pricing Manager” for you and it looks like something is preventing WP easy updates to work properly. Could you try deactivating all non-gd plugins and see if you’re able to insert the license key through the plugin dashboard?
To open a new support ticket, first select the relevant forum and then click the "New Post" button. Example: You need support for the core plugin? Click on Core Plugin support and click on the "New Post" Button.