How to restrict categories in Leaky Paywall
In Leaky Paywall Settings choose the Subscriptions tab.
Choose the Post Type and Category (under Taxonomy) that you would like to restrict. In the example below most posts are metered at 2 free articles per 31 days, but the 'Health & Wellness' category is locked down (no free articles) and only paying subscribers can view the content (Number Allowed = 0).
Note: Make sure you set the restriction exceptions at the top. Restrictions are evaluated from the top down.