Once you have purchased WordPress Theme or a plugin you should keep an eye on its upgrades and updates. It happens not weekly, but still everyone wants to use the latest tools and features while working with site administrating. Besides some updates also make your theme look more attractive visually for both leads and regular customers.
Every next version of theme or plugin differs from previous one, but not always know exactly what changes have taken place. Is such case using Change Log will help to track what changes happened.
As for a theme or a plugin the Change Log can be found in the readme.txt file in each product directory.
Also you can follow the link of Fruitfulcode themes at Themeforest, choose your favourite one and check how it has progressed from its previous version.