Forticlient licensing and registered/unregistered endpoints

Hi,

i am bit confused. I have the standard 10 Forticlient licenses. I have read the documentation and it appears that there are two versions, free and the one you need the license. 

- can you explain the difference between registered or not registered an endpoint

- can i just not register an endpoint as i only need my clients to connect in without any additional features. Does this give me unlimited vpn clients that i can connect

- is there a way to avoid the endpoint to get prompted to register the endpoint.

thanks