RICE, BRADY, and DEION are free to everyone, and they'll stay that way.
Most of the work behind them went into ideas that didn't pan out. I built four other team ratings and four other ways to pull a passer apart from his team. There's also a long list of ideas that seemed obviously right and didn't help on games the model hadn't seen.
If the site's useful to you, a coffee helps pay for the time and the computing. Donating doesn't unlock anything.