How to activate/update Revolution Slider/Visual Composer/Other premium plugin from theme package, how I can do this?

You don't need and can't activate premium plugins that provided with theme with theme purchase code. Theme already have latest plugins versions that suitable for this theme version.

All plugins and themes work without activation.

You don't need to update premium plugins yourself (you need to wait when we will release theme update with new plugin version after compatibility tests). For some themes we may not add latest plugins versions if it does not required for theme or have some problems with compatibility. We does not provide ETA for theme updates and can't say you date when some update will be released.

We can't provide any support for our theme if you update premium plugins to newer version yourself before we will release new theme version with new plugin version inside, because it may not work with this theme correctly and may not support it (tested & supported plugin version already included with theme, this is why you don't need to purchase, activate or update theme bundled plugins).