Agama pro theme come with bundled premium plugins so you get it at the price of Agama Pro theme and do not have to pay extra for them.
LayerSlider, Visual Composer & Revolution Slider are working properly without an activation code.
Only if you want to access a bundled plugins premium data like importing demo sliders or accessing to Visual Composer templates you will need to buy a license.
If you decide to buy Visual Composer license to use templates, there are next steps you need to do to activate your Visual Composer:
1) Switch from Agama Pro to any WordPress default theme.
2) Disable Vision Core plugin.
3) Disable & Delete Visual Composer plugin.
4) Install Visual Composer plugin.
5) Activate Visual Composer license.
6) Enable Vision Core plugin.
7) Activate Agama Pro theme.