How to refer to paid online courses?

Hi!

Could you please help me out with understanding how to refer to a web-conference if it can be accessed:

1 - free

2 - by password

3 - on payment?

What is the difference if i say free webinar and public webinar?

How to refer to the webinar that can be accesses by password: closed webinar or private webinar?

How to refer to the webinar that can be accesses only if you have paid for the attendance: Paid webinar?

Is it ok to say: "admission - paid"

(please, see the picture attached)

What is the word for the amount that an attendee must pay to acceess the webinar: cost/fee?

Thanx!