Trouble, your system has already been registered in the Windows 10 program, has it not? You can probably get the RTM .iso and install it without any Licensing problems. One warning, you may not want to use install media which has an embedded key like possibly your OEM copy...
Dave, the Licensing records will not be on the local install, but on some server with Microsoft. For all I know, it might be in your own OneDrive account, but that will probably remain Microsoft's secret. The Licensing is not actually linked to your e-mail, but to your Microsoft account. If you can change the primary e-mail address of your Microsoft Account, doesn't that mean it will not effect your licensing if you have to change it for some reason..?
Your...