Error Messgae: Fatal error: Allowed memory size of 67108864 bytes exhausted

How do I fix this error

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 77 bytes) in /home/csag2015/public_html/wp-content/plugins/marketpress/includes/wpmudev-metaboxes/fields/class-wpmudev-field-select.php on line 18