How do I use the flood interface?
They are two different parameters that share the same name (and can share the same value by default). Per the docs for FloodInterface:

::register():



int $window: (optional) Number of seconds before this event expires. Defaults to 3600 (1 hour). Typically uses the same value as the isAllowed() $window parameter. Expired events are purged on cron run to prevent the flood table from growing indefinitely.




::isAllowed():



int $window: (optional) Number of seconds in the time window for this event (default is 3600 seconds, or 1 hour).





The register() parameter specifies how long that flood event will be stored (remembered) after the time of registration before ::garbageCollection() clears it out. The isAllowed() parameter specifies the max number of instances that can occur within that window before isAllowed() will return FALSE