Members pro 2 error message and conflict

hi ,
when i try to go to the customize option in the appearance menu . i have encountered this error when using the Members pro 2 plugin is active . this error is stop as soon as i deactivate the plugin

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 3200 bytes) in /home/farkouh/public_html/ on line 345