Each image classified incurs a request cost. Rate limits define the limits of the quantity of requests that may be classified each month.
The request cost is calculated by the number of models that are used. For example, if two models are used (e.g. "General" and "NSFW") this will incur 2 request for every image processed.
When you use up the monthly quota of allocated requests, the plugin will cease to classify images, even when invoked. Refer to your Stackla agreement to understand your limits and contact your customer success representative to increase limits.