Services are perishable in two regards
The service relevant resources, processes and systems are assigned for service delivery during a definite period in time. If the designated or scheduled service consumer does not request and consume the service during this period, the service cannot be performed for him. From the perspective of the service provider, this is a lost business opportunity as he cannot charge any service delivery; potentially, he can assign the resources, processes and systems to another service consumer who requests a service. Examples: The hairdresser serves another client when the scheduled starting time or time slot is over. An empty seat on a plane never can be utilized and charged after departure.
When the service has been completely rendered to the requesting service consumer, this particular service irreversibly vanishes as it has been consumed by the service consumer. Example: the passenger has been transported to the destination and cannot be transported again to this location at this point in time.