error code when activating plugin

I've been working to resolve issues on my install and get snapshot working every time i activate it i get the following code

Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 778836211 bytes) in /home/causeblg/public_html/wp-content/plugins/snapshot/lib/snapshot_utilities.php on line 858

I tried allocating memory the htaccess file but still crashes