The link to the join page from the tour does not set a cookie, thus, you MIGHT be lucky that the sale gets tracked, but no click is tracked without any question and if the surfer leaves and comes back later you defiantely get nothing.
NATS does however offer a direct to join link, and any sponsor would be able to give it to you if you just ask them. They might not know right away, but they could always ask us.
NATS even allows any kind of deep linking into the site and this is explaind in our knowledge base:
http://kb.getnats.com/idx/0/068/arti...king_done.html
There is a special "page" you can link to this way called "join" which will send directly to join. So simply add /join at the end of the normal link and it will work.
Be aware that not all of your sponsors might like this and you should ask them before you use this feature. We might also add a feature at some point which lets them disable this deep linking in the NATS Admin.