Hi @maynard,
Yes, product blocks containing product feeds will automatically exclude products a person has already purchased, and we don’t attach any time-based expiration to that, so if somebody bought something many years ago, that product should still be excluded from their feed, as long as the Ordered Product event for that purchase has been recorded in Klaviyo.
Product feeds are not variant specific, meaning that if somebody purchased one variant of a product, no variants of that product will appear in a product feed they see moving forward.