Ability to use post expirator again

I added some code I found in the web in l. 475 of "wpuf-add-post.php" (see http://wordpress.org/support/topic/posts-dont-expire). Don't know why it's not already changed, but with this the post expiration function now works for me again.
I guess this function comes from the post expirator plugin? So checking the function with `function_exists` would be ideal.