From time to time we stumble about resource quotas in Microsoft Azure. So this is a good opportunity to remember the article "Azure Subscription and Service Limits, Quotas, and Constraints" which describes the limits used by default in Azure services.
So when creating a new SQL Server in an Azure subscription I ran into the message "Server response = 40652 Cannot move or create server. Subscription 'xxxx' will exceed server quota.". Honestly, first I did not check the error message, then I saw that the server quota would have been exceed. So the solution was to delete unused SQL servers in that subscription to free resources and then to create the new SQL server resource in the Azure Portal.
There's an important hint for Azure Admins in the Azure Service Limits-article, saying: "If you want to raise the limit above the Default Limit, you can open an online customer support request at no charge. The limits cannot be raised above the Maximum Limit value in the tables below. If there is no Maximum Limit column, then the specified resource does not have adjustable limits."
Anyway, each topic has a description for it's limits and there's details about that behind each topic (follow the link in the graphics to open the article).
The subscription management has limits as well.
For example, Azure SQL Database resource limits describes that the resources are measured in Database Transaction Units (DTU). See this article to understand the pricing tiers and the DTUs: SQL Database options and performance: Understand what's available in each service tier.
The graphics shows the available DTUs per pricing tier, starting with 5 in Basic up to P11.
Basically, currently there exist these models (taken from here).
So for SQL restources, Azure SQL Database has a DTU quota per logical server of currently 15000 DTUs. Which means that you can use a lot (3000 Basic databases or 1.500 S0 DBs or 750 S1 DBs, etc.) on one logical server.
So, choose wisely how to plan your services (within your Azur subscription)!