What will I pay if I run multiple instances of the same android device image I subscribed on aws marktplace?

You pay $0.60 per hour, per instance, plus any AWS platform fees, so multiple instances are billed separately. Genymotion also notes that 1 instance for 5 hours costs the same as 5 instances for 1 hour in its pricing model. Source: Genymotion PaaS (Device Image) and Genymotion on AWS

For example, 3 instances running for 2 hours would be billed as 6 instance-hours by Genymotion, before AWS charges. The marketplace listing also says the price is $0.60 / hour per instance, without Cloud platform fees. Source: Genymotion PaaS (Device Image)

Are you planning to use this for testing, demos, or a larger team deployment?