Query available RAM in Inno Setup

I need to get the available RAM to determinate some characteristics to my software.

I have this code to show my PC's RAM:

type
  DWORDLONG = Int64;
  TMemoryStatusEx = record
    dwLength: DWORD;
    dwMemoryLoad: DWORD;
    ullTotalPhys: DWORDLONG;
    ullAvailPhys: DWORDLONG;
    ullTotalPageFile: DWORDLONG;
    ullAvailPageFile: DWORDLONG;
    ullTotalVirtual: DWORDLONG;
    ullAvailVirtual: DWORDLONG;
    ullAvailExtendedVirtual: DWORDLONG;
  end;

function GlobalMemoryStatusEx(var lpBuffer: TMemoryStatusEx): BOOL;
  external 'GlobalMemoryStatusEx@kernel32.dll stdcall';

function InitializeSetup: Boolean;
var
  MemoryStatus: TMemoryStatusEx;
  RAM: String;
begin
  Result := True;
  MemoryStatus.dwLength := SizeOf(MemoryStatus);
  if GlobalMemoryStatusEx(MemoryStatus) then
  begin
    RAM := Int64ToStr(MemoryStatus.ullTotalPhys/1000000000);
    MsgBox('This PC has '+RAM+' GB of RAM', mbInformation, MB_OK);
  end;
end;

Based on How can I check system specs in Inno Setup before/during installation?

If you already have the code for GlobalMemoryStatusEx from How can I check system specs in Inno Setup before/during installation?, just use the ullAvailPhys field.

Another possibility is using WMI query:

var
  Query: string;
  WbemLocator, WbemServices, WbemObjectSet: Variant;
  OperatingSystem: Variant;
begin
  WbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  WbemServices := WbemLocator.ConnectServer('.', 'root\CIMV2');
  Query := 'SELECT FreePhysicalMemory FROM Win32_OperatingSystem';
  WbemObjectSet := WbemServices.ExecQuery(Query);
  if not VarIsNull(WbemObjectSet) and (WbemObjectSet.Count > 0) then
  begin
    OperatingSystem := WbemObjectSet.ItemIndex(0);
    Log(Format('Free physical memory = %d GB', [
      Integer(OperatingSystem.FreePhysicalMemory div (1024*1024))]));
  end;
end;

See also Is there a way to read the system's information in Inno Setup (shows, among other, how to retrieve total physical memory using WMI query).