How to make a .NET application "large address aware"?

From what I can tell you have to use the editbin utility shown in the existing answer. There does not appear to be any way to set the flag using Visual Studio .NET, it looks like they encourage people to compile for 64 bit if possible instead of using the flag

http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=93771

Add those lines to Post build:

call "$(DevEnvDir)..\tools\vsdevcmd.bat"
editbin /largeaddressaware "$(TargetPath)"

From: vsvars32.bat in Visual Studio 2017

The flag is part of the image header, so you need to modify that using editbin.

editbin /LARGEADDRESSAWARE <your exe>

Use dumpbin /headers and look for the presence of Application can handle large (>2GB) addresses to see if the flag is set or not.

For doing it automaticaly from Visual studio, please refer to this question : flag from visual studio.