I think it's always been a separately licensed extension. It's still there on my ArcGIS for Desktop 10.5 version. Did you recently upgrade but not install or enable the extension?
I'm not seeing the license in ArcGIS Administrator and it says it unavailable when I go to Extensions.
Then I came across this:
ArcGIS Network Analyst requires ArcGIS Pro (Basic, Standard, or Advanced).
That states it's an ArcGIS Pro extension.
I'm running 10.2.1 and I know I had access at one point. Figured I'd check here before calling ESRI reps.
I have it on ArcGIS 10.2.1 and it is a separate Extension. It doesn't come automatically with an Advanced license.
The newer ESRI Help, unfortunately, seems to automatically assume everyone has the latest and greatest in software, so you have to take what you find with a grain of salt.
Chris Donohue, GISP
HI Chris - I looked at the 10.5 Help for Network Analyst and although in a different format, clearly states that the Network Analyst extension is required. If you have suggestions on how to improve the Help System, there is a Feedback page you can communicate to Esri on proposed improvements. Cheers!
If you're licensed for Network Analyst with ArcGIS Desktop (i.e. ArcMap, et. al.), then the same license is used for ArcGIS Pro. There are Network Analysis "Portal" tools available in ArcGIS Pro, but these use organizational credits.
Keep in mind that the license for Pro are managed thru ArcGIS Online (unless you have them converted to use the concurrent use license manager). You or your AGOL administrator may have you checked for the core, but not for the extension. Also, if the extension is not on current maintenance, it may not be available.
ah yes...I also forget about that option since not one I would use (at this time).
I'm also not sure based on Sean's question whether the goal was to get it activated for Desktop or for Pro....a bit vague and could be read either way.