We installed or purchased a Software for Accounting & Billing for Rs. 1.5 lakh & annually we should pay Rs. 55K as AMC.

In this case,

What will be accounting entry for Rs. 1.5 Lakh? It is revenue expense as software installation charge or capitalized as Intangible assets in block-E?

Capitalizing as an Intangible Asset depends on the nature of the software and how it is used by your business.: 

If the software is expected to provide economic benefits to the business for more than one accounting period, it is usually capitalized as an intangible asset. 

Accounting Entry:

Software (Intangible Assets) Dr. 1,50,000

Cash/Bank/Supplier                     Cr. 1,50,000

Given the substantial cost of Rs. 1.5 lakh and the fact that there is an Annual Maintenance Charge (AMC) of Rs. 55k, it suggests the software will be used for multiple years, thus supporting the treatment as a capitalized intangible asset rather than an expense.

The AMC costs are typically expensed annually as they are incurred to keep the software operational, rather than improving or extending its original functionality.

Accounting Entry:

Software Maintenance Exp      Dr.    55,000 

Cash/Bank                                     Cr.   55,000

P.s. Consult with your auditor or tax consultant before making any substantial entry or changes in your financials.