You can block update in a simple way.
1. Please locate wmlp_updater.php and in line number 20, change the version number to 1111.0
2. Please locate wp-masonry-layout-pro.php and in line number 7, change the version number to 1111.0 (same number as above)
So your plugin version will be 1111.0 it will be always greater than the version of the plugin we release and there won’t be any update.
Hope this make sense and helps you out.