Metrics from all official integrations (including host metrics) are included in the $15/month/host flat pricing. Of course, them being sent will trigger that per-host billing, but that's an expected consequence of installing the agent on a host. The only caveats I know of are:

- some integrations have options to collect more timeseries. If the volume is too high, these will be marked in the documentation as billed as custom metrics

- custom integrations (including custom prometheus/openmetrics instances) are billed as custom metrics, as if they were sent through statsd

- container monitoring (enabled by default in the docker image, but not the other agent installations) is included up to 10 concurrent containers per host ; additional containers are billed on-demand