Preemptible instances function like normal instances but have the following limitations:

-> Compute Engine might stop preemptible instances at any time due to system events. The probability that Compute Engine will stop a preemptible instance for a system event is generally low, but might vary from day to day and from zone to zone depending on current conditions.

-> Compute Engine always stops preemptible instances after they run for 24 hours. Certain actions reset this 24-hour counter.

-> Preemptible instances are finite Compute Engine resources, so they might not always be available.

-> Preemptible instances can't live migrate to a regular VM instance, or be set to automatically restart when there is a maintenance event.

-> Due to the above limitations, preemptible instances are not covered by any Service Level Agreement (and, for clarity, are excluded from the Compute Engine SLA).

-> The Google Cloud Free Tier credits for Compute Engine do not apply to preemptible instances.