This is a Joomla system plugin for module versioning.
In the articles ther is an option to store revisions (versions) of the article when the article is saved.
This plugin adds the same functionality to the modules.
Note: Only core settings are saved! This plugin does not save setting stored by other extensions like Regular Labs - Advanced Module Manager.
Install and activate the plugin.
In the settings of the plugin you can set how many revisions should be stored.