Imagine we have a VM with OS version X and middleware SW (e.g. SQL Server) version Y.
(1) Who manages (i.e is responsible of) currency for OS/Middleware software in a VM? Is it Azure or the account that created the VM resource?
(2) If the OS/Middleware SW version becomes obsolete, is it (automatically) upgraded to the next version OR a new VM needs to be designed?
A virtual machine on Azure is Infrastructure as a Service, which means you don’t worry about the infrastructure (hardware, connectivity, power etc.), but you are responsible for everything that runs on the VM, in terms of software. That includes the OS, any application, any patches to these, any security settings and all configuration.
If you want Azure to manage the version of software, you need Platform as a Service, such as Azure SQL or Azure DevOps.
I hope this helps.