What is the source and all the information of this mantra:
Om Shreem Shree Dharaya Trailokya Mohanaya namaha?
The exact verse is found in Garuda Purana, Purva Khanda, Achara Kanda, Section 1, Chapter 29. These are the mantras are used in Trailokyamohini rite for the gaining of various objects and it is described by Lord Hari himself.
त्रैलोक्यमोहिनी वक्ष्ये पुरुषोत्तममुख्यकाम्।
Hari said :-I will now describe the Trailokyamohini rite (fascinating the three worlds) of the foremost of male beings, its adoration and the mantram called Śridhara which yeilds religious profit, desire and wives.
ॐ श्रीं (श्रीः) श्रीधराय त्रैलौकयमोहनाय नमः॥
क्लीं पुरुषोत्तमाय त्रैलाक्यमोहनाय नमः॥ ३॥
Srim, salutation unto the holder of Sri and the enchanter of the three worlds. Klim, salutation unto the foremost of male beings, the enchanter of the three worlds.
The Mantra you have quoted is from Garuda Purana - Achara Kanda - Section 1 - Chapter 30 - Verse 8 . " Shreedhara (vishnu) Vidhi Dharma" . But is little different.
This mantra is used in worship of Shridhara manifestation of Lord Vishnu.
ॐ ह्रीं श्रीधराय त्रैलोक्यमोहनाय विष्णवे नमः आगच्छ ॥ .1.30.8 ॥
Om Hrim Shreedharaya TrailokyaMohanaya Vishnave Namah Aagchhya
Om Hrim ,Salutation unto Shreedhara , Trilokyamohana and Vishnu.
shridhar (श्रीधर)- The bearer of Śrī who listens-to-prayers”):—One of the twenty-four forms of Viṣṇu through which Nārāyaṇa manifests himself. He is accompanied by a counterpart emanation of Lakṣmī (an aspect of Devī) who goes by the name Medhā.