Gameomatic breaks site when license # is added

I assume there's some conflict with another add-on somewhere, but after activation and when I add in the codecanyon license #, my site's wp-admin crashes. Here's what the apache error logs are showing:

PHP Fatal error:  Uncaught Error: Call to undefined function wp_create_nonce() in /public_html/wp-includes/functions.php:1860\nStack trace:\n#0 /public_html/wp-admin/includes/file.php(2445): wp_nonce_field()\n#1 /public_html/wp-content/plugins/gameomatic-giant-bomb-post-generator/update-checker/Puc/v4p8/Factory.php(178): request_filesystem_credentials()\n#2 /public_html/wp-content/plugins/gameomatic-giant-bomb-post-generator/update-checker/Puc/v4p8/Factory.php(42): Puc_v4p8_Factory::getThemeDirectoryName()\n#3 /public_html/wp-content/plugins/gameomatic-giant-bomb-post-generator/gameomatic-giant-bomb-post-generator.php(199): Puc_v4p8_Factory::buildUpdateChecker()\n#4 /public_html/wp-settings.php(418): include_once('....')\n#5 /public_html/wp-config.php(107): require_once('....')\n#6 /public_html/wp-load.php(50): require_once('....')\n#7  in /public_html/wp-includes/functions.php on line 1860, referer: /wp-admin/