session eCart and login members

Hello,

I created a cart that uses SESSIONS. It works fine.
Now I thought about, only let customers buy if they are registered to the shop.
So I created an register formular, with with email check, and this works (thanks security assist and data asist) well!

Now my question. What happens if the customer closes the browser during registration and confirming the registration link in the email he gets.

I think the session stored cart is gone, right?

How can I temporary store the cart the customer shopped?

So, if the customer closes the browser, it should be restored, and if not, the cart should be created from the session.

Can this be done with cookies? Or should I store the cart in cookies from the beginning?

Cheers
Denis