I just wanted to share a solution I found to fix the error 500 problem, if like me you cannot edit the PHP memory limit of your hosting plan.
ini_set('memory_limit', '3000M'); at the beginning of your wp-config.php file, and it should work just fine !
If for some reason you can't edit your wp-config.php, just add it at the beginning of the plugin file (but you'll have to do this after each plugin update).
Hope this helps! Thanks to Mike for the fix.