Hello there!

I want to play rock and I don't want to go into altered scales and similair stuff. My goal is to master major scale and its modes and of course maj and min pentatonic scale. Is it possible for Pebber's subscribers to pay for only certain lessons?

No, I don't think so. You sign up, and you follow his curriculum. I'm not sure why you would want to limit yourself by pre-defining what you think you need. If I were you, I'd let the master show you what you need.