Review for non existing products

Hi,
I would like to use the plugin to display all reviews on my website. I have products whose lifecycle is quite short (1-2 months), and I would like to keep those reviews on my website even when the product is not on sales on the website anymore.

Hence, my question is the following: how can I add reviews for a product that is not on the website anymore ? Is there a feature or a trick that I can use ?

Thanks in advance.
Best
Christelle