Do sims cost monthly other than the pilot?

I apologize if this is the wrong section, first time posting.

I’ve been messing around with the pilot sim as I’ve been learning how to program my simcom 7600A-H module and was curious if more sims cost monthly or if I can just buy data and only pay for what I use.

I guess my question is, if I were to order more sims, do I have to pay monthly for each or do I only have to pay if I need each sim to have a separate number?

Thanks