Thanks for the question.
In Cursor we have a few core features:
Tab Completion, AI Chat, CMD+K, Composer and Agent
While Tab is the first and simplest to learn and use, the Composer and it’s Agent mode are arguably the most powerful, being able to write multi-file code changes from one prompt.
CMD+K (or CTRL+K on Windows) and the AI Chat are the only features that work with an API key and no Pro plan.
If you get a Pro plan, you can then use your API Key with the Composer too, because your Pro plan unlocks some additional models that are used in Composer, but are not the primary model.
Tab and Agent mode are the two features that will likely never work with an API key, irrespective of a plan or not.
You can find out more about all these features on our documentation site, here: