This is still a very early version of the service. Account management is currently limited to signing up via Stripe and getting an email with your API key and a how to get started guide :)
I can make the free tier more obvious, you really don't need an account or credit card to get started with the API that's why "Get Started" links to the docs. You can just copy and paste the commands/code examples and get started. I see now that's it's not at all clear and will fix this.
Otherwise I'd say the pricing units are really just the number of calls. A really interesting idea might be to have a comparison on the site between my service and Maxmind's web service!
Some really basic account management like you describe is very much in the works. There're currently no accounts on the site. But it's something I'd like to do possibly offering a higher free tier quota to users who sign up, so that I'm able to communicate with them and have stats on conversion etc