Any monitored Service will have all the benefits activated. Update a service by: Monitors>Services>Toggle the monitor ON>Save. The reverse is done for turning monitors OFF.
Where you have reached the limit of included Monitors on your plan, an Additional Monitor will be automatically purchased. You can also upgrade your plan tier at anytime.
A technical note here - we will start reporting on a service from when it reaches the beta testing stage, not just when it is in production (live).