Rest API sanctrum

Hello I am following this tutorial https://www.twilio.com/blog/build-restful-api-php-laravel-sanctum and I see similar method on other websites too where they are using for login the $user->createToken method. I would understand to the register but I don't understand the login part.

If I login with rest api and using the code which the website recommended to use then every single time when I am login then new token will be created. Does Sanctrum have token validation instead creating everytime new token? Thank you in advance the answers.