Trello offers three paid options: Trello Gold, Trello Business Class, and Trello Enterprise. They’re ways to build on to the free Trello experience—Trello Gold offers a way for individual users to take their Trello use to the next level, Trello Business Class is intended for multi-user teams to have more fine-grained control over who can access their boards, and Trello Enterprise allows for concierge support as well as additional security features important for large-scale enterprise teams.

via Trello Enterprise vs. Trello Business Class vs. Trello Gold – Trello Help