JBoss Operations Network was available in two flavors - with monitoring support and without. As of last year it's only available with monitoring support. The latest release - 2.4.1 - is available now and does not require a separate license to be installed.
The evaluation period for all JBoss products is 30 days, JON included and there are no technical restrictions. There is no license necessary for an evaluation. I believe you agree to Red Hat licensing terms with the click-through or when you register.