Hi Matthew,
At 10.5 the licensing level changed models to be more function-based. The workflow you describe was primarily used from the 10.2.x to 10.4.x versions and was redundant. I'll outline the workflow you need for 10.5.x below:
There are four different license levels for ArcGIS Server, all corresponding to a different function:
1. GIS Server
2. Image Server
3. GeoAnalytics Server
4. GeoEvent Server
To properly install the GeoEvent Server on a separate machine please do the following:
1. Install the ArcGIS Server software
2. License this software with the GeoEvent Server license or provisioning file
3. This action dedicates the ArcGIS Server to run the "GeoEvent" function
4. Install the GeoEvent Server software
5. License the software with the same GeoEvent Server license or provisioning file
6. This activates the GeoEvent software and allows you to build real-time services
This new function-based workflow ends up saving your licenses for dedicated functions, as you don't have to double up on licenses for installations.
Hope this helps,
Chris