As you know, Alexa-hosted skill provides AWS Lambda, Amazon S3, Amazon DynamoDB and AWS CodeCommit features  with some limits.
In documentation, it says that the "resource usage is limited to the AWS Free Tier".
I know that Lambda and DynamoDB (and CodeCommit) have "always free" options. While Amazon S3 doesn't . It's only "12 months free".
Could you please tell whether it means that after 12 months, Alexa-hosted skills will start to generate non-zero bills?