We strongly recommend you keep your registered email address with us up to date, otherwise we might not be able to help you in case of a lost license. To change your registered email we need a serial of one of your LinPlug licenses to proof that its a valid request from the license holder. | 
What happens is this: we look up what email the serial has been registered before, and change all registrations of this email to the new email you just sent us. Furthermore you will get a reply what serials are registeed with your new email. In case you miss a license in that reply its probably registered with a different email, in such case just repeat the change request for the missing products.
