Q & A Plugin

I have purchased and installed the plugin.
There is no documentation for the plugin, after activating the plugin I have entered a question but I cant write any answer, as I receive the following error: Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 523800 bytes) in /home/devmeyna/public_html/wp-includes/post.php on line 402

Please advice