This code will get the time of installation and date of when windows was installed you need a button and 2 labels.

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function GetWindowsInstallationDate():TDate;
var
  Reg : TRegistry ;
  StartDate : TDate; //12:00 A.M. on January 1, 2000
begin
  Reg := TRegistry.Create ;
try
  Reg.RootKey := HKEY_LOCAL_MACHINE ;
  If Reg.OpenKey('SOFTWARE\Microsoft\Windows NT\CurrentVersion', False) then
begin
  StartDate := EncodeDateTime(2000,1,1,0,0,0,0);
  Result := IncSecond(StartDate,Reg.ReadInteger('InstallDate'));
  end else
  begin
    messagedlg('This information is not available on this Operating System',mtError,[mbOK],0);
    exit;
    end;
  finally
  Reg.Free;
  end;
end;
function GetWindowsLife(InstallDate : TDate): String;
const
  SecsPerDay : Integer = 60 * 60 * 24;
  SecsPerHour : Integer = 60 * 60;
  SecsPerMinute : Integer = 60;
  SecsPerSecond : Integer = 1;
var
  TimeDiff, Days, Hours, Minutes, Seconds : Integer;
begin
  TimeDiff := SecondsBetween(Now,InstallDate);

  Days := TimeDiff div SecsPerDay;
  Dec(TimeDiff, Days * SecsPerDay);

  Hours := TimeDiff div SecsPerhour;
  Dec(TimeDiff, Hours * SecsPerhour);

  Minutes := TimeDiff div SecsPerminute;
  Dec(TimeDiff, Minutes * SecsPerminute);

  Seconds := TimeDiff div SecsPerSecond;

  Result := Format('%d Days %d Hours %d Minutes %d Seconds',[Days, Hours, Minutes, Seconds]);
end;



procedure TForm1.Button1Click(Sender: TObject);
begin
  Label1.Caption := 'Install Date: ' + DateTimeToStr(GetWindowsInstallationDate);
  Label2.Caption := 'Windows LifeTime: ' + GetWindowsLife(GetWindowsInstallationDate);
end;