PRTG Manual: Using PRTG in the Cloud
PRTG Network Monitor offers two options to monitor your network: PRTG on premises and PRTG in the cloud. With PRTG on premises, the core server and local probe run within your network. PRTG in the cloud is the PRTG cloud solution, where we at Paessler run the core server and cloud probe for you. The PRTG web interface for monitoring configuration and reviewing monitoring data is the same for both, PRTG in the cloud and PRTG on premises.
Paessler Website: PRTG in the Cloud – Service Description
Paessler Website: FAQ – PRTG in the Cloud