This plugin is having very bad structure of storing values into the database.
This plugin stores values into wp_postmeta table in the form of serialize data. So if in the future, you want to change domain name or want to move website on different domain name, You have to first deserialise data as per your new domain. Then it will work.
But if you have more than 4k pics and more than 100 gallery, you have to 100 times deserilise data and update in the database for your new domain. In short, it increases work load and consume lots of time for just serializing and deserializing database.
This is highly disappointing that such a well written plugin is using such a baby database structure.
I will highly recommend not to use use this plugin, specially in high volume gallery website.