Non Metered Services

Hello team, as per the below document there are some restrictions on user-defined tags. One of the restrictions states that user-defined tags on NON-METERED services will not be populated in the cost management suite.

Public Document: https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/allocation-tag-restrictions.html

1. What is the definition of NON-METERED services?
2. What services can be categorized as NON-METERED?
3. Can RIs be classified as NON-METERED?