If I understand correctly, a plan always has a price and duration. We're operating on a freemium model, where some content is available to payed users but also some content is available to users who just register.
It is kind of possible to emulate it by specifying a price of 0 euros, but it looks like a hack; there is still a price shown, there is still payment information asked, and there is still a duration.
To us, it would be great if there is a 'register' or 'free plan' option that doesn't show the price, doesn't ask for payment information, and ideally is perpetual (instead of recurring).