I have not visited this location yet.
This location seems to have followed a different pricing scheme from the other EWO stations in the past.
In an archived version of the Elektrotankstellen-Netz page on EWO website there's a list of the stations which is identical to today's list minus the EWO-Hauptsitz, but there's an asterisk next to this station: "* Die Elektrotankstesse Alpnachstad ist im emobility-Netz (www.emobility.ch) eingebunden und somit kostenpflichtig".
On Chargemap there's a closeup of the text on the side of an EWO station saying it's free, but the picture is not dated and there's no way to confirm whether it was really taken at this location. The wider angle pictures show a different charging station model than at other locations.
On Google Maps, there's a marker "be.ENERGISED Charging Station" here showing 0/2 available Type 2 22kW.
The oldest version of the E-Mobility page I could find for the EWO website is from May 2015 and it does mention "Alpnach" as part of the 4 at that time. But I think this might be the -Dorf location, not -Stad because Chargemap had comments back to 2015 on that one.
In Zusammenarbeit mit der Zentralbahn realisierte das Elektrizitätswerk Obwalden bereits an vier Standorten im Kanton Obwalden Elektrotrankstellen. Bis auf weiteres können Sie Ihr Elektrofahrzeug an den Bahnhöfen Alpnach, Sarnen, Sachseln und Giswil kostenlos mit «EWO NaturStrom» tanken.
I can't find any single version of the archived pages where -Stad is mentioned. The version from January 2016 still only mentions "Alpnach" without detail, the versions from March 2016 onward say "most stations" equipped.