Transfer to and from other AWS resources is free (see their FAQ).

hanoz · on Nov 30, 2016

I'm not seeing that in the FAQ. In my reading it pointedly leaves open the possibility of incurring AWS egress charges when transferring to LightSail.

merb · on Nov 30, 2016

https://aws.amazon.com/de/blogs/aws/amazon-lightsail-the-pow... - VPC peering.

Which means it's free since transfering data from one VPC to another one or peering is free (at least it was with bare aws)