There seem to be errors showing on the site which makes me think that the purchase process might be broken.
eg on the form to fill in details for purchase all of the boxes display an error
"<br /><b>Notice</b>: Trying to get property 'name' of non-object in <b>/html/shop/website/components/com_shop/views/shop/tmpl/default.php</b> on line <b>28</b><br />"
before you enter anything.
This makes me think that the form is broken - please advise how to purchase the pro version? I don't want to enter payment details on a obviously broken form!
PS Has your host updated to a new php version and your shopping cat component not been updated?