Many thanks for your insights and comments.

It is good to know that SQL Server does not take more memory because it doesn't need it. I was afraid that there was...

Good to know that the amount of memory is sufficient.

The queries that are running on the databases are heavily joined. In peak hours those queries are executed all the time....

Thanks for the responses so far. Here are some answers.

Select * from sys.dm_os_performance_counters

where counter_name = 'Page life expectancy'

Returns:

object_name ...

It is possible that SQL Server does not need more memory, but I find i curious that the memory usages stays exactly the same each time, while the databases are...

Sorry, post in wrong discussion.