asign subscription on registration

Hello, I'm using membership plugin,
I have defined 3 subscription plans (15 días trial, 6 meses, 1 año). When I register I have the option to choose one of the 3 subscriptions, but when I finish the process, the user is not assigned any subscription method.
Is there a way to do it automatically??

If I configure membership general options, and I edit user registration -> use subscription and set a subscription, then the user is always asigned this subscription no matter what subscription plan is selected on registration.

Any idea how to solve this?

Thanks