To enable the Auto Registration feature
In this situation, you previously disabled Auto Registration, but you now want to use it. To do so, you must enable the Auto Registration SMF service by using the regadm enable command.
To attach named support credentials to a registered system for support purposes
You previously registered products anonymously, but for support purposes, you now need to attach named support credentials to these products.
To explicitly register a system, independent of the installation or upgrade process
You want to explicitly register your system, independent of the installation or upgrade process.
When you use the regadm register command to register your system, the service tag data is transmitted to the Oracle Product Registration System immediately upon running the command. There is no need to reboot the system for a service tag to be sent.