Once you have registered a new song on the "Your songs" page, select the registered song and click "Send song" at the top right corner.
You will need to provide an email address for the user you want to send your registered song to. You have the option to provide a personal message.
The other user will receive an unlicensed copy of your registered song. Your own registered song will still remain.
Purchasing a sample license is not required to be able to send your registered song to another user.
This function can be used to send a registered song to a label or another artist - if you are not the one who is responsible for licensing the new song.