I don´t know how insert data in an enterprise geodatabase using a Geoevent Service, I get data with an input "Poll an External Website for JSON" and I draw a map using the output "Add a feature" but also I wanted to store the received data in a enterprise geodatabase.
Thank you in advance
You need to have registered an ArcGIS Server as a Data Store (the ArcGIS Server on the GeoEvent machine is automatically registered when you install GeoEvent, FYI). That ArcGIS Server needs to have a published feature service. When you have that, you can set up the "Add a Feature" or "Update a Feature" outputs and select the desired feature service to write/update features. Feature services require enterprise geodatabases, so once this is up and running, you're doing what you want to do: "store the received data in a enterprise geodatabase".
Check out the "Introduction" tutorial at the GeoEvent gallery: GeoEvent Extension tutorials—Real-time Data Feeds and Sensors (10.4) | ArcGIS for Server It contains what you need to set up Add/Update outputs that write to geodatabases.