Zero, if the tool is Trayzero: it's free and open source under GPLv3, so five people install it five times and nobody buys a seat. OmniFocus sells one seat per person, Things is a separate purchase per Apple platform, and Todoist bills per user per month. The harder question is how your team stays in sync when the data never leaves each phone.
Published August 31, 2026 · 7 min read