It’s OK to re-register the CloneDVD 5 on the same PC. There is no time limit. But please note that the serial number is bundled with the Email Address you used to register for the first time. That is to say, it’s not allowed to change the email address when you re-register. Or our system will refuse the registration. The Email address is the only key to retrieve your serial number in the future.
Therefore it’s highly suggested to register the software by using the Email address you used to fulfill the Purchase Form in your first registration.