Recently viewed

Theme settings > Recently viewed has one setting: Expiration. Products viewed longer ago than this many days (30 by default) drop off the visitor's recently-viewed list.

The list is stored in each visitor's browser — it's private to them, works per device, and survives between visits until it expires or they clear their browser data.

The list itself is displayed by the Recently viewed products section — add it to product pages, the cart, or anywhere else.