How to install and configure a wpmudev plugin in a client site

I was testing about how to install and configure a plugin from wpmudev white labeled, in order to give my client support and the necesary updates.
I have created a fresh install of wp in order to do some tests, imaging that it is my client site.
Bare in mind that it is a individual site, not a multisite, where the client ask me to install and configure the plugin in his site, and give him support.
I dont know if this will be the right procedure, but i did so:
Firstable i asked to my client ( my fake client), to create a new administrator in order to be able to enter an install de wpmudev dashboard and enter my API key. Afterwards i have installed a random plugin (ultimate branding) and test how this worked.
I have realised that when (my fake client) enter to the site with his username he is not able to see the link to wpmudev dashboard, so he can't have access to my api key. He only have access to the ultimate brandig plugin. Perfect!:grinning:
But here comes my doubts...
1º This is the right way to do this kind of things??Or there is another better way??
2º Is this the safest way in order to avoid my clients to have access to my api key, or there is another way?
3º Finally i have tested a situation where i disable my client's site from my control panel, even i have deleted the site in my control panel, but the site still has the access to the plugin and it works fine. It wouldnt have to disappear??

Thanks, and i hope i've explained well.