No. of users in your Org account exceeds the user licenses purchased.???

No. of users in your Org account exceeds the user licenses purchased.???

This message has just appeared at the top of my ZM

"No. of users in your Org account exceeds the user licenses purchased. Please buy additional licenses to avoid deactivation of excess users."

I have no idea what this means, What is an "Org" account I did not know I had one and in any case I have not made any changes or added users, and what licences are they talking about?

Futhermore the word "buy" is a active link and when I click on it I get no explanation, in fact it goes to the subscription page and there is no mention of any "Org" account and I only have one user anyway.

Mark