Tor and IP Address - Quick Question

While using Tor, how often does your IP address change? The reason I ask is because I want to join a paid membership site but their members' area kicks you out if you log on from 10 different IPs in one day.

 

I have a question about IP too. When using Tor, whose IP is displayed? Exit node's? I have ShowMyIP Firefox add-on and every time I use Tor I check my IP at
http://ip-address.domaintools.com/
http://www.leader.ru/secure/who.html
http://www.dnsstuff.com/tools/aboutyou.ch
This is always same like what ShowMyIP displays, so I guess everything works fine, but it somehow mismatches what I see in Vidalia's Network Map.
There I can see nodes' IPs but none of them is the one that is shown in ShowMyIP or above mentioned sites. Can anyone explain, please?

 

While using Tor, how often does your IP address change? short anser depending on how may ips are there you are bouncing of ,can be any where from 2 to 222 as it relays you to many IPS .thats there idea of hiding you .