Yes, absolutely.
Upon request SIM cards can be moved to a “Deactivated” state. The “Deactivated” state does not allow a SIM to establish a data connection. You are free to do this at any point in the month.
SIMs in “Deactivated” state are not billable but can be moved back to “Activated” state upon request.
If a SIM is moved from “Activated” to “Deactivated”, M2M One will credit your account any unused amount of your current data plan subscription for following months.