Do companies pay for movies to use their logo for advertisement, or do movies have to pay the companies for using their logo in films?

When you see a company logo in a film or TV show, the company has paid for it. It's called "product placement." In fact, if you pay close attention to movies and TV shows, you will see when a company has refused to pay the film's production company for the product placement because the logo is blocked out or obstructed, usually in post-production much like how genitals often get censored in post-production. Doing it in post-production rather than simply covering the logo on the set when filming give the company whose logo it is every opportunity to pay up.

The most common example I see of logos being blocked is on cars. You will see what is clearly a Volkswagen or a Ford or whatever in a TV show or movie, but when the car is heading towards you in a shot, instead of seeing the circle chrome Volkswagen logo or oval chrome and blue Ford log, you just see a circle or oval that's the same color as the car, appearing as if the actual hood ornament was pried off, though it wasn't and is really just blurred out with the same color as the car in post-production. 

Apparently, car companies in particular have gotten quite sick of being extorted for money by movie production companies taking it upon themselves to use their cars in their movies and then demand payment. I say this because it has become extremely common to see the logos on cars blurred out in movies and TV shows, so common that I'd say that their logs are blurred out about half the time.

By the way, the late 70s is really when product placement started, and even then, it was widely frowned upon. Prior to then, it was so frowned upon that nobody did it. It was seen as artistically selling out. Films that had product placement often got jeered with accusations that they'd compromised their artistic integrity by selling out becoming what was basically a long term commercial. So in movies before the late 70s, when you saw a box of cornflakes, for example, it was always some made up brand, usually with some paper cover over the actual label. The same went for soft drinks. You'd never see a Coke or a Pepsi but only ever see a can that just generically said "Cola" on the side if the movie or script called for having a can of Cola. Before the late 70s, all the brands and logos you ever saw in movies were always fictional, not real brands or logos. Even in the Herbie franchise, a series of Disney movies about a Volkswagen Beatle named Herbie that could think and drive for itself and was the main character in the movie, Herbie was stripped of all its Volkswagen logos. Of course, movie viewers all knew it was a Volkswagen Beatle, but no logos anywhere and the characters never used the word "Volkswagen" or "Beatle" at any time. Now James Bond may have been an exception with his Astin-Martin cars and Walther-PPK guns, but I'm not sure that that really counts, James Bond films being foreign films, British films, and American movie standards were a completely separate animal, especially from Hollywood, the industry cultivating this image that it was ideal and pure and beyond corruption, as wholesome as apple pie.

The companies pay to advertise