app/code/Magento/Persistent/README.md
This module enables setting a long-term cookie containing an internal ID (random hash to prevent brute force) of persistent session for customers. Persistent session data is kept in the database, so it's not deleted after a few days and can be maintained for as long as needed. The database session stores the customer ID and some data from the real customer session that needs to be synchronized (e.g., number of items in the shopping cart). For registered customers, this information is synchronized to the persistent session if they select the "Remember me" checkbox during their first login.
Before installing this module, note that this module is dependent on the following modules:
Magento_CheckoutMagento_PageCacheThe Magento_Persistent module creates the persistent_session table in the database.
This module modifies the following tables in the database:
quote - adds column is_persistentAll database schema changes made by this module are rolled back when the module gets disabled and setup:upgrade command is run.
For information about a module installation, see Enable or disable modules.
Extension developers can interact with the Magento_Persistent module. For more information about the extension mechanism, see Plugins.
The dependency injection mechanism enables you to override the functionality of the Magento_Persistent module.
A lot of functionality in the module is on JavaScript, use mixins to extend it.
The module dispatches the following events:
persistent_session_expired event in the \Magento\Persistent\Controller\Index\UnsetCookie::execute methodpersistent_session_expired event in the \Magento\Persistent\Observer\CheckExpirePersistentQuoteObserver::execute methodFor information about an event, see Events and observers.
For more information about a layout, see the Layout documentation.
You can get more information at the following articles:
Cron group configuration can be set at etc/crontab.xml:
persistent_clear_expired - clear expired persistent sessions