// 存值
$request->session->put(key,value);

// 取值
$request->session->get(key);

// 清空
$request->session->flush()

You can read the documentation
http://laravelacademy.org/post/3261.html

The laravel file is really too rough. The session is probably a trap for many people. If it is not a normal return control layer function, you need to call session()->save()

There are two main points to pay attention to when using session add, delete, modify and check:
First, the session.php configuration is correct;
Second, the add, delete, modify, and check functions are not written incorrectly.

For the source code analysis of session, please see: Laravel Study Notes: Session Source Code Analysis (Part 1)