Only an Owner or admin can change billing. Members see seats and tokens.
Owner or admin selects Buy 1000 tokens on Settings → Billing for a €50 pack that does not expire. The same page is where seats change. Business is €49 per sender per month, or €39 annual.
Members can open Billing and read used of licensed seats and the token balance. They cannot buy a pack or change the seat count. Teammates themselves are free.