in themeforest it says that with BeTheme there's also other plugins bundled with it. But how do we activate the premium versions for those plugins? I'm interested for Revolution Slider to be specific
Purchase codes (license keys) are not included for plugins that are bundled into the theme. It’s because of the Themeforest license & agreements. This applies to all themes, of course. However, there is no need to use this code because the plugins are fully functional without it.
Something like the “Free” version of a plugin does not exist. All bundled plugins are included with extended licenses, and users can use these plugins within the theme without needing to purchase them separately. This is standard and according to ThemeForest rules.
More information about the bundled plugins, you will find in the link below: