The Adobe Launch team has made Launch available for free for all Adobe partners and customers of partners. Previously, Launch was only available for non-production use for Exchange partners only.
Now, with Launch being made available for production use for all customers of Exchange partners, your Launch extension can be used by your entire customer base regardless of if they are an Adobe customer.
To request access, your customers must fill out this form and include the name of the partner they are associated with in the comments of the form: https://www.adobe.com/offer/request-launch.html.
For a refresher on Launch and building extensions, see the overview and getting started guide.