Raise Memory Limit
This lets you set the PHP memory limit for WordPress. All in One SEO Pack sets this when the plugin is executed by WordPress. This is may get overridden by other plugins, your server configuration, your php.ini file, or if you have WP_MEMORY_LIMIT defined in your wp-config.php file. Here is the official WordPress documentation regarding setting your memory limit.
Raise Execution Time
This lets you set the PHP execution time for WordPress. This may be required if you get timeout errors when trying to perform functions in the WordPress administrator dashboard or on your site. All in One SEO Pack sets this when the plugin is executed by WordPress. This is may get overridden by other plugins, your server configuration, or by your php.ini file.
This lets you specify whether you want All in One SEO Pack to use output buffering for writing Meta Titles. Some themes and plugins will overwrite your Meta Titles because they execute after All in One SEO Pack is executed. Use this to try to override them and ensure that the Meta Titles are written by All in One SEO Pack.
This is the output from a PHPINFO command executed on your server. It provides information that may be useful in troubleshooting problems with All in One SEO Pack.