Implement subscription management and ordering

core/templates/billing.html

@@ -34,6 +34,9 @@
                 Last payment
               </li>
             </ul>
+            <form action="{% url 'portal' %}">
+              <input class="btn btn-lg btn-dark btn-block" type="submit" value="Subscription management">
+            </form>
           </div>
         </div>
 
@@ -46,6 +49,7 @@
           </div>
         </div>
 
+
       </div>
     </div>
   </div>