I recently made the switch to WooCommerce from another E-com provider and my number one need was the ability to assign serial keys (passcodes) for our courses automatically and immediately when customers buy one of our courses. The StoreApps Serial Keys plugin does just that. Simple to use and straightforward setup; and support is great too. I love the fact that customers can easily access their serial keys in their my account page if they misplace the Thank You email. Great plugin, a must-have if you sell online courses.