# Codes and promotions > How free practice is funded for the people you invite, and how access codes fit in. Each partnership has a sponsorship agreed with Neural Bits. A practice invite made with your key carries that sponsorship unless you send `"sponsorship": "none"`; the `offer` in its answer says what the person will get (`free_days`, `trial_pass` or `none`). Free passes are limited by caps on the code, the partnership and the month. When a cap is reached, new invites offer the Trial Pass instead — the person still gets practice set up for the job. The caps apply to your partnership as a whole, never to an individual you invite, and the person learns about a free pass of their own only after they sign in. Neural Bits can also give you access codes: a link `https://www.interview100x.com/join/{code}`, optionally with `?job=` to carry the job into setup. Codes are managed by Neural Bits; ask your contact for one.