Hi @JayGr
I think this link is more helpful than the one you looked at
https://experienceleague.adobe.com/en/docs/analytics/implementation/vars/page-vars/products
Products as such do not function like eVars and do not persist across page views, so no expiration as such can be set.
Products also live with the Analytics events like prodView, scCheckout, purchase, that they are sent with.
If you set the s.products variable and forget to send an appropriate event with it, a "prodView" is implicitly assumed.
Merchandising eVars can be configured to be used within the products syntax.
Cheers from Switzerland!