利用tp5框架封裝好的Cookie類和Session類。若發現過期時間沒有生效，可以試試清除快取。

登入頁面Login.php

<?php
/**
 * Created by PhpStorm.
 * User: zjl
 * Date: 2018/11/1
 * Time: 15:21
 */
namespace app\admin\controller;

use think\Controller;
use think\Request;
use think\Session;
use think\Cookie;

class Login extends Controller{
    public function index(){
        return $this->fetch('index');
    }
    public function login()
    {
        $request = Request::instance();
        //判斷post過來的資料是否被提交過來
        if($request->isPost()){
            $data = $request->param();
            //對提交的資料進行判斷
            if(empty($data['user']) || empty($data['password'])){
                exit(json_encode(array('status'=>0,'message'=>'使用者名稱或密碼不能為空')));
            }
            //對資料進行過濾
            $username = addslashes(trim(stripslashes($data['user'])));
            $password = addslashes(trim(stripslashes($data['password'])));
            $config_session = [
                'prefix'            => 'admin',     // session 名稱字首
                'expire'            => 7200,        // session 過期時間
                'use_trans_sid'     =>  1,          //跨頁傳遞
                'use_only_cookies'  =>  0,          //是否只開啟基於cookies的session的會話方式
            ];
            $session = new Session();
            $session->init($config_session);
            $session->prefix();
            $session->set('user',$username,'admin');
            $session->set('password',$password,'admin');
            $config_cookie = [
                'prefix'    => 'admin', // cookie 名稱字首
                'expire'    => 1800, // cookie 儲存時間
                'path'      => '/', // cookie 儲存路徑
                'domain'    => '', // cookie 有效域名
                'secure'    => false, //  cookie 啟用安全傳輸
                'httponly'  => false, // httponly 設定
                'setcookie' => true, // 是否使用 setcookie
            ];
            $cookie = new Cookie();
            $cookie->init($config_cookie);
            $cookie->prefix();
            $cookie->set("sessionId",session_id());
            $this->redirect('/index.php/admin/Index/index');
        }
    }
}

主頁面Index.php

<?php
/**
 * Created by PhpStorm.
 * User: zjl
 * Date: 2018/11/1
 * Time: 15:21
 */
namespace app\admin\controller;

use think\Controller;
use think\Request;
use think\Session;
use think\Cookie;

class Index extends Controller{
    public function index(){
        if(Cookie::has("sessionId",'admin')){
            if(Session::has('user','admin') && Session::has('password','admin')){
                $user = Session::get('user','admin');
                $password = Session::get('password','admin');
                $this->assign('user',$user);
                $this->assign('password',$password);
                return $this->fetch('index');
            }else{
                //'session過期了';
                $this->redirect('/index.php/admin/Login/index');

            }
        }else{
            //'cookie過期了';
            $this->redirect('/index.php/admin/Login/index');
        }
    }
    public function logout()
    {
        Session::flush();
        Cookie::clear('admin');
        $this->redirect('admin/Login/index');

    }
}