It is software for internal use ,which is part of appendix of AS-26. APENDIX provides the illustrative application of the PRINCIPLES laid down in the STANDARD to internal use of software
"The cost of a software acquired for internal use should be recognised
as an asset if it meets the recognition criteria prescribed in paragraphs 20
and 21 of this Statement"
further para 20 and 21 states
20. An intangible asset should be recognised if, and only if:
(a) it is probable that the future economic benefits that are
attributable to the asset will flow to the enterprise; and
(b) the cost of the asset can be measured reliably.
21. An enterprise should assess the probability of future economic
benefits using reasonable and supportable assumptions that represent
best estimate of the set of economic conditions that will exist over the
useful life of the asset.
There is future economic benefit since the software will provide its support for 3 years.
further it states
13. The depreciable amount of a software should be allocated on a
systematic basis over the best estimate of its useful life. The amortisation
should commence when the software is available for use.
Which in this case is 3 years and should be written off in 3 years (which i mentioned earlier)
OP asked for reference of Accouting Standard , I gave reference of appendix of AS-26
but yes, I should have mentioned that it is appendix to AS