Why the ladder has no trap in it
Nine editors on Starter costs €39 plus six times €10, which is exactly €99 - the price of Team. From the tenth editor onwards Team is cheaper, and you get unlimited hubs and adoption analytics with it. That is deliberate: there is no team size at which stacking extra editors onto Starter beats moving up, so you never have to work out whether you are on the wrong plan. Yearly works out the same way, because the annual prices are the monthly ones times ten.
Readers are free, and that is not a detail
You pay for the people who write documentation, never for the people who read it. A design system that charges per reader is a design system nobody reads - and documentation that nobody reads is an expense, not an asset. So invite the whole engineering team, the product managers, the new joiner in their first week. It changes nothing about your bill.
What happens when you stop paying
Your documentation stays reachable until the end of the period you paid for, and you have thirty days after cancelling to export everything. We do not lock the door on the last day of the month. A tool that only works while you keep paying is a tool nobody should trust with the description of their own design system.