If you are a registered user of Alpha Blender Pro you may upgrade at no charge to any newer release. Just download the latest release of Alpha Blender Pro and install it without uninstalling the previous version. This will preserve your registration.
If the registration code is no longer present on your system just re-enter it like the first time and restart the program.
If for any reason your registration code becomes invalid or lost just send an e-mail to firstname.lastname@example.org together with the details of your previous registration. You will receive a new code via e-mail at no charge as soon as I have validated your old registration data.