$49 is only for Hostbill core updates excluding modules, order pages, Client Area themes.
$99 you will get updates for 1-2 Modules, Apps, Order pages, Client Areas
$199 for 2-3 Modules, Apps, Order pages, Client Areas.
$299 for 4-5 Modules, Apps, Order pages, Client Areas.
$399 for Unlimited Modules, Apps, Order pages, Client Areas.
All for 12 months. So to get updates for all you have to pay $448 every 12 months