Is this a question on whether you can use italki or Skype on an iPad or Notebook PC?
If it is, then you can log onto italki via a browser with the username or email address that you've registered with. Skype you can use on either device, as long as you log on correctly.
I am not an iTalki employee, I am just trying to help. If you need a response from iTalki you should contact them directly.