As of 11/29/2017, Dan Darden has decided to provide his pro version of the plugin for free. His version includes IOTA as a currency in WooCommerce. Thanks Dan! You can install it from the releases page into your WooCommerce installation as a ZIP file. It is important to read the readme.txt file; After you've read it, you only need to set a few variables to get set-up. Enjoy!