Wifi requirment and cloud service

I would like to know the answers to the following questions about Purple Air before purchasing some PurpleAir devices. I appreciate your thoughts.
1-How much data I would need for wifi each month for a purple air device if I run it 24/7? Actually, I want to run 6 of it at one location with a shared wifi.
2- Is the the purple air cloud service free?
3- How long can our measurement data be stored on the cloud server?

For #2 and #3, read the Terms of Service. The collected data belongs to PurpleAir, and while there is no ongoing cost to host a sensor, there is (or can be) a small cost to retrieve that data through the API, and there are limits on how much data can be retrieved at a time.

Thank you. Where can I find the Terms of Service?

Hi @meamouei, PurpleAir data is stored indefinitely and will always remain available.

Our terms of service is available here: Terms of service – PurpleAir, Inc..

The power draw and data usage can be found here: Q: How much power does a PurpleAir sensor draw, and how much bandwidth/data does it use?.