How many Nest security cameras can work together? or is each one a separate charge?

Each Nest Cam would require its own Nest Aware subscription if you want multiple Nest Cams to have video history available. With that said, the Nest Aware subscription price would be full price for the first subscription and all additional subscriptions would be at a discounted rate. For example, if you were to purchase the 5-day Nest Aware, the first subscription would be $5 a month and additional subscriptions would be $3.