WPUltimo is a plugin for turning a multi-site install into a premium WordPress network for sites. Features include the ability to signup new clients, manage subscriptions, let clients select templates, automatically provision a site, as well as custom domain mapping. There are both free and premium addons. Addons provide support for WooCommerce, AffiliateWP, MailChimp, and more. The lifetime package includes all free and premium plugins, chat and email support, and use for creating unlimited networks.