Core configuration of Recently Viewed/Compared Products | Synchronize widget products with backend storage | Magento 2

Question

Can someone explain what enabling this option do:

Store -> Settings -> Configuration -> Catalog -> Catalog -> Recently Viewed/Compared Products:

Synchronize widget products with backend storage: Yes/No

I can't find any information about it... I found this: https://docs.magento.com/m2/ce/user_guide/marketing/products-viewed-compared.html

However, this option is not included in the documentation. I am using Magento ver. 2.2.4.

UPDATE:

In addition, there are two more option not included in the docs:

Lifetime of products in Recently Viewed Widget:

Lifetime of products in Recently Compared Widget:

Can someone explain?

UPDATE 2:

I have theme installed so I thought it might be "add-on" from theme, however I found this in vendor\magento\module-catalog\etc\adminhtml\system.xml so I'm guessing it's Magento 2.2.4 default feature:

<group id="recently_products" translate="label" type="text" sortOrder="350" showInDefault="1" showInWebsite="1" showInStore="0">
            <label>Recently Viewed/Compared Products</label>
            <field id="recently_viewed_lifetime" translate="label comment" type="text" sortOrder="40" showInDefault="1" showInWebsite="0" showInStore="0" canRestore="1">
                <label>Lifetime of products in Recently Viewed Widget</label>
            </field>
            <field id="recently_compared_lifetime" translate="label comment" type="text" sortOrder="40" showInDefault="1" showInWebsite="0" showInStore="0" canRestore="1">
                <label>Lifetime of products in Recently Compared Widget</label>
            </field>
            <field id="synchronize_with_backend" translate="label" type="select" showInDefault="1" canRestore="1">
                <label>Synchronize widget products with backend storage</label>
                <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
            </field>
        </group>

Answer 1

I have found the answer in the code that located by path: vendor/magento/module-catalog/Model/Product/ProductFrontendAction/Synchronizer.php

/**
 * Service which allows to sync product widget information, such as product id 
with db. In order to reuse this info
* on different devices
*/