Hey,
As far as I know the emulation stops once you exceed the quota.
You can verify your quota ...
=> within the Threat Emulation tab of the gateway overview within SmartConsole
=> via the Threat Emulation command line (TECLI): "tecli show cloud quota"
=> within the Check Point UserCenter
The quota exists to save yourself and the Check Point Cloud, so that if you should be under attack, that you do not "waste" all of your emulations in a short time (which is unusual for normal use cases).
There is also the sizing tool available which lets you see how many emulations would be required for your environment.
More details regarding this can be picked up at SK93598.