Google Analytics Tracking & Thank You Page

Hi,

I’m in Google Analytics setting up a goal to track how many people completed check out. To do this, I need to paste in my thank you page, what exactly should this be as I didn’t think this was a set static url? I use Clickbank for my checkout and S2member states that my thank you page is:

http://www.petsitterplanet.com/?s2member_pro_clickbank_return=1

Is this the url I should use for the thank you page?

The URL below is what seems to be the actual thank you page, however as you can see at the end of the url, it says “preview” so again this doesnt seem like the actual thank you page:

http://www.petsitterplanet.com/?
s2member_pro_clickbank_return&s2member_paypal_return=1&s2member_paypal_proxy=clickbank&s2member_paypal_proxy_use=x-preview

So my question is, what is the actual URL of the thank you page that people are directed to after completing checkout??

Thanks

https://wordpress.org/plugins/s2member/