Licences and Rules
When you download a model, you get two things: the weights, and a licence — the legal terms attached to them. People read the first and skip the second, then discover at launch that the terms forbid exactly what they built. This short chapter is the one to come back to before shipping anything on open weights.
What a licence controls
| Term | The question it answers |
|---|---|
| Commercial use | May I sell a product built on this? |
| Redistribution | May I host it, or ship the weights to users? |
| Derivatives | May I fine-tune and release my version? What counts as “derivative”? |
| Cap | Is there a user or revenue limit before I need a separate deal? |
| Naming | Must I credit the lab, or say “built with” something? |
| Acceptable use | What must I not do — weaponisation, surveillance, disinformation? |
| Jurisdiction | Whose law governs the terms, and can they change them? |
The common licences
Permissive (Apache 2.0, MIT) lets you use, modify, and sell almost freely, keeping the notice. DeepSeek’s R1 and Mistral’s flagship models use these — they are the reason those weights spread so fast. Community licences (Meta’s Llama, Google’s Gemma) are open in practice but carry conditions: a very large user cap, a naming requirement, and an acceptable use policy that you must pass downstream. Research-only licences forbid commercial use entirely. A model card is the document that states all of this, alongside intended use, evaluation results, and known limitations — its licence section is the part that governs you.
Open weights are not open source
For software, “open source” has a firm meaning, and the industry’s body, the Open Source Initiative, tried to extend it to AI in 2024. The hard question is the same as in the first chapter: if you cannot see the data or the training code, is the system open, or merely downloadable? The debate is unresolved, which is exactly why a permissive software-style licence tells you more than the word “open” does.