Need to transfer my subscription from old broken doorbell to new door bell.
Please someone help.
Add New Doorbell to your current subscription, delete/remove the old Doorbell from your subscription.
Here is the replacement Ring device section for subscription transfer, which should help in this case. 
Got a replacement device after troubleshooting with Ring, but my subscription and/or videos did not transfer over.
This process should be automatic as long as the old device was not deleted from your account before the new device was set up and the transfer took place. If the old Ring device has been deleted already, but the videos and/or the subscription did not transfer over, please Contact Us.