add_features.rb

class AccountsAddFeatures < ActiveRecord::Migration[6.0]
  def change
    add_column :accounts, :features, :citext, array: true, null: false, default: []
    add_column :users, :features, :citext, array: true, null: false, default: []
  end
end

application_policy.rb

class ApplicationPolicy
  # ... pundit stuff

  def enabled?(feature)
    user.enabled?(feature) || user.account.enabled?(feature)
  end

  def disabled?(feature)
    !enabled?(feature)
  end
end

featured.rb

module Concerns
  module Featured
    extend ActiveSupport::Concern

    class_methods do
      def with_feature(feature)
        return none if feature.blank?

        where("? = ANY(features)", feature)
      end
    end

    def enable!(feature)
      features << feature
      features.uniq!
      save!
    end

    def disable!(feature)
      features.delete(feature)
      save!
    end

    def enabled?(feature)
      features.include?(feature.to_s)
    end

    def disabled?(feature)
      !enabled?(feature)
    end
  end
end