WPMUDEV plugin install and full member access

I installed the WPMUDEV-plugin on a first site via my computer at home. I was never asked for the API, but at some point entered my log-in details to WPMUDEV. Still the Dashboard showed me as a free member, which I am not, I am a full member.
Next day, at my office computer, I logged in to my website, and I had full access to all member features.
Just now, again at my OFFICE computer, I installed the plugin into another website. Again no question for the API, and again I am handled like a free member on this other, new site. On the previous one it still works properly.
Does registration just take so much time? Or did I do something right by coincidence the first time but don't know what?
Please help, how do I register a website as a full member to get access to themes, plugins etc.