I am setting up a site which will eventually have paid subscription content, can anyone advice which service works best with K2?

Many thanks ,

You can try Akeeba Subscriptions as well.

Thanks for responding, but I may not have been clear in my request, what I am looking for is a user subscription service, where people pay to enable them to view content. I can't find something like this on the Akeeba website.

thanks,

Actually Akeeba subscriptions is offered as a developer's extension.
www.akeebabackup.com/download/akeeba-subscriptions.html

I am afraid I do not know of another similar extension. I am sure that there will be some available at the JED.