Hello Caridad,
I have tested Post-expirator and there is a strange thing : It's working when you create the article in the backend (as the norml way of doing). But if I create the article with a Cred Commerce form and place it as draft until the payment is validated, then, the post-expirator does not work. You have to go in the backend and save the article in order to see postexpirator appears.
I have posted a ticket in the Post-expirator forum but still don't have any answer from now.
Regards
Pat