Windows – Do programs on Inactive Virtual Desktop still use the memory in Windows 10

This is normal behavior.
Perhaps your question might be "How to make a process run only one 1 virtual desktop as of windows 10"

This can be done with the below AutoHotKey script, which accepts two shortcut keys:

• F11 : Will write the titles of all current windows and their virtual desktop numbers to a text file specified in the parameter FILENAME that is found at the beginning of the script.
• F12 : Reads the text file and moves all the windows it can find by their title to the specified virtual desktop.

Copy the following text into an .ahk file, possibly changing "FILENAME", "F11" and "F12". Double-click the file to start it executing. It will create a green "H" icon in the traybar that you can right-click and select Exit to stop. If you always want this script to execute, copy it to the user Startup folder at C:\Users\<user name>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup.

This script requires to download from the Github project windows-desktop-switcher the DLL VirtualDesktopAccessor.dll and storing it in the same folder as the AutoHotKey script. It might not work for Windows 10 versions below 1809.

The script itself is below and is programmed for only one monitor. It does not create the virtual desktops, so they should be created before running it. It worked for me, but should be tested. As it's using undocumented features, it might stop working some time in the future.

DetectHiddenWindows Off
SetTitleMatchMode, 2

FILENAME = C:\Temp\possaves.txt

hVirtualDesktopAccessor := DllCall("LoadLibrary", Str, "VirtualDesktopAccessor.dll", "Ptr") 
MoveWindowToDesktopNumberProc := DllCall("GetProcAddress", Ptr, hVirtualDesktopAccessor, AStr, "MoveWindowToDesktopNumber", "Ptr")
IsWindowOnDesktopNumberProc := DllCall("GetProcAddress", Ptr, hVirtualDesktopAccessor, AStr, "IsWindowOnDesktopNumber", "Ptr")

global numdesktops := GetDesktopsNumber()

F11::  ; Write list of "desktop@title"
EnumAddress := RegisterCallback("EnumWindowsProc", "Fast")
global numwins := 0
global file := FileOpen(FILENAME, "w")
DllCall("EnumWindows", "Ptr", EnumAddress, "Ptr", 0)
file.Close()
return

F12::  ; Read list and execute
global result
Loop, Read, %FILENAME%
{
    word_array := StrSplit(A_LoopReadLine, "@",, 2)  ; Omits periods.
    hwnd := WinExist(word_array[2])
    if (hwnd)
        DllCall(MoveWindowToDesktopNumberProc, UInt, hwnd, UInt, word_array[1] - 1)
}
return

GetDesktopsNumber()
{
    RegRead, cur, HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\SessionInfo\1\VirtualDesktops, CurrentVirtualDesktop
    RegRead, alldesktops, HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VirtualDesktops, VirtualDesktopIDs
    return floor(strlen(alldesktops) / strlen(cur))
}

EnumWindowsProc(hwnd, lParam)
{
    WinGetTitle, title, ahk_id %hwnd%
    if title {
        desktopnum := GetHWNDDesktopNumber(hwnd)
        if (desktopnum >= 0) {
            numwins := numwins + 1
            line = % desktopnum "@" title "`r`n"
            file.Write(line)
        }
    }
    return true
}

GetHWNDDesktopNumber(hwnd)
{
  global  numdesktops, IsWindowOnDesktopNumberProc
  Loop, %numdesktops% {
    ix := A_Index - 1
    windowIsOnDesktop := DllCall(IsWindowOnDesktopNumberProc, UInt, hwnd, UInt, ix)
    if (windowIsOnDesktop == 1)
      return A_Index
  }
  return -1
}