Return billable seats href for paid groups only

ee/app/helpers/billing_plans_helper.rb

@@ -155,8 +155,11 @@ module BillingPlansHelper
     "#{EE::SUBSCRIPTIONS_URL}/gitlab/namespaces/#{group.id}/renew"
   end
 
-  def billable_seats_href(group)
-    group_seat_usage_path(group)
+  def billable_seats_href(namespace)
+    return unless namespace.group?
+    return if namespace.actual_plan_name == Plan::FREE || namespace.trial_active?
+
+    group_seat_usage_path(namespace)
   end
 
   def offer_from_previous_tier?(namespace_id, plan_id)