install Start8 on customer's system

I configure individual computers of my customers with Windows 8 and want to install, pay and activate Start8. After that, customer should be on his own. How should I proceed in terms of e-mail address, and ensure that start8 survives eventuell reinstalling of the operating system. Using and accessing the customer's e-mail is out of question, because email isn't yet set up on this computer, and for principle. Administrating his mail address at stardock is mainly out of question. I do have my own one e-mail-address and that's it. Using and paying start8 is perfectly "in question."

Oh, and how will I manage my own several computers for Start8, but I have just one mail address and mail is just on one computer.

Thanks.

Peter.