Forgetting to shutdown an instance is a common cause of extra charges, yet it is possible to avoid that by settings alarms, reminders or auto-shutdowns.
AWS
Use the CloudWatch service to set alarms. For more information, refer to Amazon CloudWatch.
GCP
It is possible to stop the instances on schedule. Please refer to Save money by stopping and starting Compute Engine instances on schedule.
Alibaba
It is possible to set alarms via Cloud Monitoring. For details and instructions, please refer to Cloud Monitoring - Manage alarms.
Azure
Use the auto-shutdown feature: in the Virtual Machine details, go to Operations > Auto-shutdown.