I am pretty sure what I am talking about is cognitive dissonance theory as developed by Leon Festinger.
Cognitive dissonance is a discomfort caused by a conflict of two cognitions. In this case 1) "I like this book" and 2) "I did not pay for that book even though I should have".
Now there are a few ways to resolve with that dissonance. A way to do that is to change one of your cognitions, you could 1) tell yourself that the book wasn't good at all and therefore not worth paying for, or 2) pay for the book because you liked it - either way you eliminated the controversy.
That only works if you believe you should have paid for it. An increasing number of people believe they are entitled to free copies because that's what they've been getting all their lives.
Cognitive dissonance is a discomfort caused by a conflict of two cognitions. In this case 1) "I like this book" and 2) "I did not pay for that book even though I should have".
Now there are a few ways to resolve with that dissonance. A way to do that is to change one of your cognitions, you could 1) tell yourself that the book wasn't good at all and therefore not worth paying for, or 2) pay for the book because you liked it - either way you eliminated the controversy.