Partner Events publishers create a registration to enable a first-party experience through which users can create partner topics you define. A Partner Registration mainly describes the following:

The resource (partner topic) type that users see on Azure portal’s Event Grid Create Partner Topic. Each Partner Registration defines a type of partner topic. Hence, it is possible to define more than one type through additional Partner Registration instances.
The URI to a web page an Event Grid partner hosts that provides the ability for users to create a partner topic.
The general contact information for a user to get support from you (an Event Grid partner) when issues or questions about the partner topic type you are defining.

Event Grid Partner RegistrationMicrosoft

Event Grid Partner Registration

Microsoft

Event Grid Partner Registration

Microsoft

Event Grid Partner Registration
Microsoft