In order to register for the Researcher Account (12 months free), you will still need to fill out your billing details as a placeholder. You won’t be charged for the first 12 months (note the date on when your first bill will be issued as shown in the image below). After the 12 months, you will need to remember to downgrade your plan to ‘Open Use’ otherwise you will be charged as per a normal ‘Consultant’ subscription. More details about each subscription can be found here.
How to Update My Personal Subscription/Payment Details?