If you see the following message, your NATS license has expired:
NATS LICENSE This Version of NATS is licensed to: <your company name> This Version has EXPIRED! The license is overdue. The NATS ADMIN has been disabled until the license is renewed.
Please contact one of our staff: NATS has not stopped working for you, but your administration section and access to the API has been shut down. You need to get a new license from us and restart your Apache Web server.