Adi Lakshmi is the first form of Ashtalakshmi or one of the forms of Goddess Lakshmi. She is the Goddess of eternal wealth, wealth which has no ending and no beginning, meaning it flows continuously.
Adi Lakshmi is often depicted as having four arms and she holds a lotus and a white flag in two of her hands and in her other two hands, she gestures Abhaya and Varada mudra. She is seen seated on a lotus.
Adi Lakshmi is the Primeval Lakshmi and often referred to as Mahalakshmi.
This form of Goddess Lakshmi is an ancient form of the Goddess and referred to as an incarnation of Lakshmi as daughter of Sage Bhrigu.
Adhi Lakshmi resides with Lord Narayana(Vishnu) in the Vaikunta. She is also known as Ramaa meaning the one bringing happiness. She is seen serving Lord Narayana in this form and it symbolises her serving the whole creation.
Actually Adi Lakshmi can be seen as an attempt by the ancient people to give a form to the creater of the whole universe.
It is said that the whole creation emerged out of her and she and Lord Vishnu are not separate but they are together one entity.
In many places, she is also depicted as sitting on the lap of Vishnu.
Adi Lakshmi Stotra:
sumanasa vandita sundari maadhavi chandra sahodari hemamaye
munigana vandita moksha pradayani manjula bhashini vedanute
pankaja vaasini deva supoojita sadguna varshini shaanti yute
jaya jaya he madhusudhana kamini adi lakshmi paripalaya ma
Meaning:
One, who is worshipped by all the good people, who is pretty and the one who is the sister of the moon and looks like she is made of gold, and saluted by all groups of sages , who grants salvation and talks sweet words, who is praised by the vedas and lives in a lotus flower, who is worshipped by all the devas and showers good qualities on people and who is the personification of peace, Victory to Adi Lakshmi, the darling of the killer of madhu, Please protect me forever.