Signing up costs nothing
A teacher account is free. You can browse the Bureau Library, build your own question banks and run a live Signal Check with your class without paying for anything.
An activity is bought once, not rented
Buying a Case or an Operation gives you permanent access to it. You can run it with this year's class, and next year's, and the one after that, as many times as you like. There is no per-class charge and nothing expires.
Schools subscribe on top
A school subscription covers its teachers, and puts every child in the school under one record, so a pupil taught by two teachers is one agent, with progress that follows them rather than splitting in two.
Students never pay and never sign up
There is nothing for a child to buy, and nothing for a parent to buy either. A class code, a codename and a PIN is the whole of what a student needs.