Here we are discussing how to enable persistent shopping cart in Magento 2.

In Magento 2, a persistent cart is one of the relatively effective features to decrease the abandonment cart.
It allows storing the product in the shopping cart even when the customers sign out your site.

Below are the steps to enable persistent cart in Magento 2.

Login to Magento 2 Admin, go to menu Stores -> Configuration -> Customers -> Persistent Shopping Cart.
Leave the checkbox Use system value empty.
Choose “Yes” option for this field.
Set the time for the updating of the persistent cookie in the Persistence Lifetime field. The used default value is 31,536,000 seconds.
Enable Remember Me to show a checkbox on the Login page that allows saving the shopping cart information.
It is optional if you want to set default option “Remember Me” once they login to your site.
Set “No” option for Clear Persistence on Sign Out to ensure that all shopping cart information is saved.
Then, click on Save to enable the persistent shopping cart function on the storefront.
In the Persist Shopping Cart field, select “Yes” if you want to keep the persistent cookie when the session cookie expires.