NOTE: Following the launch of JW8 in October 2017, self-hosting the player is now only available to Enterprise customers. New Free license customers with accounts created before mid-September 2017 will not have access to self-hosted player files and license key (source here).
If you are an Enterprise customer, you should be able to access your license key in your JW Player account.
In the left-hand navigation menu, under the Players section, click on “Tools”. This is where you will find your license key.
Your license key will be useful to self-host the player.
Below is an example that you will find in your JW Player account :