How many moderators can I invite?
The number included is part of your plan and listed on the pricing page; moderators are free to the people you invite.
The number of moderators included comes with the plan you chose for the event and is listed on the pricing page alongside the photo allowance.
Moderators cost the people you invite nothing. They need a free Mosaikin account, because that is how they sign in and how the invitation finds them, but they are not asked to pay for anything.
You can add and remove moderators freely, before, during and after the event.