When you purchase a license your email address is used in the license creation. Its important that the email-address is a valid one when you make a purchase because that is where your license will be sent to, but after that it doesn’t really matter.
A number of customers have requested there license be changed to a new email address. This can only be done by disabling the old license and creating and sending a new one so I’d rather not do it.
If you really want this then just send me a payment of �5 to paypal@jthink.net and a covering email and I’ll do it.