The rules for using someone else's thing - written by the one who made it.
Imagine you download a free program that removes the background from photos. A window pops up with text - long, boring - you click "Accept" and forget about it. That's the license. You just agreed to rules for using someone else's thing. You didn't buy anything, you don't own anything. You got permission, under certain conditions.
Those conditions can stay almost invisible until you grow. Many companies that build artificial intelligence give away their code for free - with a catch hidden in the text of the license. It's free while your company is small. But once you grow big enough to compete with them, the license stops you or makes you pay. The threshold is often set artificially high - say, 700 million monthly active users, the limit in Meta's Llama license, so that no ordinary person, no small business, ever reaches it. The catch isn't aimed at you. It's aimed at the next big rival.
That's why the license isn't a formality, it's a boundary. It decides whether you can sell something made with someone else's code. Whether you can change it. Whether you can give it to a friend. Whether the company whose product you already use can later tell you "stop" - and you actually have to stop.
Generosity has a price
The big AI company doesn't give away its code out of generosity. It gives it away because that's how it wins millions of people - people who use it for free, get used to it, build a habit on top of it, at no cost to the company while they're small. The license is the barrier hidden behind the generosity. It lets everyone in, but shuts the door exactly in front of the one who might grow big enough to stand beside them.