What is Nitya Kalyanam
Nitya Kalyanam is the celestial wedding of the Lord, celebrated every day. Nitya means daily and kalyanam means wedding. In a temple kalyanam, the festival images of the Lord and his consort are married with the rites of a Hindu wedding.
At Sri Lakshmi Narasimha Swamy Temple, Yadagirigutta, the wedding is of Lord Narasimha and Goddess Lakshmi, the pair the temple is named for. The temple offers Nitya Kalyanam for a couple and lists it among its daily sevas; its own seva list calls it Kalyanothsavam.

What devotees seek
Couples, especially the newly wed, traditionally take part in the Lord's wedding seeking a blissful married life with his blessings. The celestial wedding is also performed for the well-being of all humanity, not only of those who sponsor it.
Because it is offered for a couple, it suits the occasions of a married life: the first year of a marriage, a wedding anniversary, or a renewal of a marriage's promises before the Lord.
What happens
A temple kalyanam follows the shape of a Hindu wedding. As performed at Tirumala, for example, the place and articles are first sanctified, and the Lord's commander, Vishvaksena, is worshipped. The family lineages of bride and groom are pronounced. The bride is given in marriage (kanyadanam), and the Lord ties the sacred thread of marriage (mangalya dharana). The bride and groom play with flower balls, exchange garlands, and the ceremony closes with the waving of lamps.
Which of these rites Yadagirigutta performs, and in what form, could not be confirmed from an official source.
The story of how Lakshmi chose the Lord is told in The Bride Who Chose.
What you receive
When you book through VedaJyoti, you receive a recorded video of the kalyanam.