There is a lump sum due at the time of cryopreservation. This pays for the cost of transportation, cryopreservation protocols, and also for ongoing costs of maintenance for the cryonics patient. This lump sum is normally covered with a dedicated life insurance policy.
Cryonics organizations also have membership dues, which are separate from the cost of the cryonics life insurance. There are no additional costs due once a member is in cryopreservation.