What's the cost? I'm I am using this services?
You're telling me that My Photo Stream will be shut down on July 26
I'm not sure if I'm using this service.
What's the cost to me?
and
method of payment?
Question marked as
There is no cost. The service is being shut down on July 26th. To know if you are even using My Photo Stream, open your Photos App and look for My Photo Stream. If you don't see it, you don't use it.