You mean that they clearly keep a track of almost everything we do on the internet while using their "masked" IP?
Most (if not all of them), yes.
Then even if paid (or highly paid ones), I believe all of them will be able to have all the data whatever you utilize through their services? What about VPS like Amazon AWS?
Even if paid, this does not guarantee that they don't keep any logs which might help to identify you.
You definitely shouldn't rely on this.
Using a VPS, of course the network activity gets logged. How else would it be able to easily proof how people abuse their service to do illegal stuff?
Do they also keep track of everything that's being done inside their remote area? Even if they don't keep any track of it, will my ISP be able to track what I'm doing in there?
Probably, they do.
Without any logs, considering you are using encrypted communication properly (e.g. no root certificates from an ISP installed on your computer like in some countries) then no, the ISP won't be able to track anything you do there.
