Using ASPState database in the AG cluster with multiple teams using the same ASPState
As a rule it's only one ASPState database per server but we need it to be able to accommodate multiple Web applications.


Your company just dictated your answers and infrastructure, sadly.


  Is it possible to use one ASPState with multiple Web applications? If it is, then how?


Apparently so:


Stack Overflow Answer
Maybe it is or isn't a good idea?



  Should this ASPState database be a part of the AG group?


If you're going to use AGs then it doesn't have to take part in it but it'll need to be loaded and properly setup on all replicas. If you put it in an AG, then you'll only have a single AG for all applications which may or may not be a good thing, depending on the application requirements.

Since the ASP state database is really just about throw away session state data, if there is a failover it won't make a real difference.


  If it's part of the one AG than other AG's won't be able use it.


That's true. If it's not in an AG but loaded on each replica by itself not in an AG that should work as I reference above.