Hi Gaurish,
You may have an incorrect idea about the HA behavior. HA for Prime Infrastructure is meant for server redundancy, not load sharing.
There will be only 1 server active at a time, this means that you are unable to share devices between the 3 servers.
In HA setup, all servers manage the same devices.
The same license files can be applied to individual servers. If you decide to use HA, only the Primary server needs to have the licenses installed; the Secondary servers, will inherit them.
Hope this helps.
Luis