Delphi实现限定软件使用时间的方法

unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
 Registry, Dialogs;
type
 TForm1 = class(TForm)
  procedure FormCreate(Sender: TObject);
 private
  { Private declarations }
 public
  { Public declarations }
 end;
var
 Form1: TForm1;
implementation
{$R *.DFM}
procedure TForm1.FormCreate(Sender: TObject);
var
  registerTemp : TRegistry;
  curDate : TDateTime;
begin
  registerTemp := TRegistry.Create;
  with registerTemp do
  begin
    RootKey := HKEY_LOCAL_MACHINE;
    //判断是否初次运行程序
    if OpenKey('Software\MySoftware',True) then
    begin
      if ReadBool('Runned') then
      //不是第一次运行
      begin
        curDate := Date;
        if (curDate-ReadTime('LastRunTime'))>=ReadInteger('Duration') then
        begin
          //当前的系统时间超出了使用期限
          ShowMessage('试用版已到期');
          exit;
        end
        else
        begin
          DeleteKey('LastRunTime');
          WriteTime('LastRunTime',Date);
        end;
      end
      else
      begin
        //初次运行程序
        DeleteKey('Runned');
        WriteBool('Runned',True);
        //设置试用期限30天
        WriteInteger('Duration',30);
        //写入当前运行时间
        WriteTime('LastRunTime',Date);
      end;
    end
    else
    begin
      ShowMessage('Fails!');
    end;
    CloseKey;
  end;
end;
end.