Implenting Min Max memory configuration in Alwayson
The current setting is set to the default max value and that is something not which I want.


You should change your max memory setting away from the default. Its a dynamic setting that does not require a restart of sql server service. Bear in mind that running reconfigure it will flush out the plan cache.

Refer to my answer here for more details.


  Each of the server has 24gb of memory. The total size of the databases on each node is 105gb


Start with 21GB as max memory provided you are running only SQL Server (no SSIS, SSRS, SSAS,etc). Leave 3 GB for OS.

Depending on the database activity, the RAM (24GB) seems to be low. You should look out for low memory notifications to see if server is having memory pressure.