Scenario:
I have mikrotik router board and acquired ISP connection via Fiber.
They provided me one /30 public pool which i configured on my Mikrotik WAN.
I acquired /24 public ip pool from APNIC and asked my ISP to route the /24 pool to my /30 mikrotik wan ip, and all is ok and my clients get public ip and works without Natting.

Now I have acquired one ASN from APNIC and it's something like AS123456.

My question is What is the benefit of getting my own ASN? and how can I configure it in the mikrotik? Do I have to involve ISP ?

My question is What is the benefit of getting my own ASN? and how can I configure it in the mikrotik? Do I have to involve ISP ?

The ASN has to do with BGP. To use it, you must establish BGP sessions with your ISPs. If you're currently only single-homed, it's easier for you to just let your ISP announce your prefix for you and route it to you with static routing.