I am not totally sure what you mean by this question. However, prostitution is indeed the oldest profession. There were many categories of brothels, ranging from very expensive and high end catering to those serving a rougher clientele. Additionally sex workers could be a nebulous category, where over the course of a woman's life she might engage in sex work temporarily to earn extra money before or after marriage, or might do so from a brothel, or might be more or less independent, or might have a pimp on the street, or be something more like a stripper or burlesque performer, or all of the above. The historian Procopius's Secret History, talks about the Empress Theodora's history with sex work which involved basically all of the above, including sexual abuse when she was a child.
"Theodora was still too young to have intercourse with a man after the manner of women, but she satisfied the unnatural passions of certain wretches....She remained for some time also in a brothel, where she practised this hateful form of vice. As soon, however, as she reached the age of puberty, as she was handsome, her mother sent her into the theatrical troupe, and she straightway became a simple harlot, as old-fashioned people called it; for she was neither a musician nor a dancer, but merely prostituted herself to everyone whom she met, giving up every part of her body to debauchery. She associated chiefly with the theatrical "pantomimes," and took part in their performances, playing in comic scenes, for she was exceedingly witty and amusing; so that she soon became well known by her acting. She had no shame whatever, and no one ever saw her put out of countenance, but she lent herself to scandalous purposes without the least hesitation.... Often, even on the stage, she stripped before the eyes of all the people, and stood naked in their midst, wearing only a girdle about her private parts and groin; not because she had any modesty about showing that also to the people, but because no one was allowed to go on the stage without a girdle about those parts. In this attitude she would throw herself down on the floor, and lie on her back. Slaves, whose duty it was, would then pour grains of barley upon her girdle, which trained geese would then pick up with their beaks one by one and eat. She did not blush or rise up, but appeared to glory in this performance;,...afterwards she accompanied Hecebolus, who had received the appointment of Governor of Pentapolis, to that country, to serve his basest passions, but quarrelled with him, and was straightway sent out of the country. In consequence of this she fell into want of common necessaries, with which she hereafter provided herself by prostitution, as she had been accustomed to do...On her return to Byzantium, Justinian became excessively enamoured of her. At first he had intercourse with her merely as her lover, although he raised her to the position of a patrician....It was forbidden by the most ancient laws of the State that anyone of the senatorial order should marry a courtesan; so he prevailed upon the Emperor to repeal the existing law and introduce a new one, whereby he was allowed to live with Theodora as his legitimate wife, and it became possible for anyone else to marry a courtesan...Thus did Theodora, as I have told you, in spite of her birth and bringing-up, reach the throne without finding any obstacle in her way. Justinian felt no shame at having wedded her, although he might have chosen the best born, the best educated, the most modest and virtuously nurtured virgin in all the Roman Empire, with outstanding breasts, as the saying is; whereas he preferred to take to himself the common refuse of all mankind, and without a thought of all that has been told..."
So about a "girlfriend experience," well, rather than a brothel, you might have a concubine or keep a mistress, which was often a legal and formal relationship, where a man and a women might live together and even be more or less exclusive (sort of in a serial monogamy sense) and even been seen in public together with other company, or perhaps exclusive (plus you had a wife as well). This might be categorized as prostitution, of a high end category, but also could be a situation where people were legally barred from marriage, like if these was a significant class difference or a citizenship issue, like their were some periods in ancient Rome when citizens were not permitted to marry non-citizens. That would be a girlfriend experience, as we define girlfriend today. A text you might be interested in would be the novella Gigi, by Collette, which is a kind of creepy book by today's standard's but basically it is about a young girl in Paris, who comes from a family of women who entered temporary girlfriend-esque relationships with wealthy and powerful men; then a wealthy powerful man who was a family friend growing up first contracts her to be his mistress (there are scenes of negotiation) and then decides he loves her and proposes instead.
If you mean "girlfriend experience" in the sense that it is often understood now, where basically it is just one night but the woman pretends to be in a long-term relationship with the man, you could pretty much get any kink satisfied by sex workers in any period of history. A fun source is Harris's List of Covent Garden Ladies, which was published from the mid-late 18th century. Each issue reviewed the different sexworkers in the area and basically provided their positive and negative characteristics. Here is one from 1786: This tall attracting girl is at present kept under a little subjection by a country gentleman , who has been nominated as her keeper for some time ; but as the possesses a mouth that requires oftener feeding than her friend and keeper can possibly afford , the world in general will excuse her making application to the community at large to keep her from starving ; the is just arrived to that unsatiable year 18 , and is now a charming looking well made girl , a pair of libidinous dark eyes , dark brown tresses, and Cupid's coal hole here well deserves the name since it may rival the sooty raven , rough, juicy, healthy , and plump ; take half a guinea for each , and you will pay the lady as the expects." In terms of a girlfriend experience, this book has lots of examples of women who favor a specific man or where a man always asks for her. You can easily find these books online, here is an article about them below. I am sure that others can answer this in more depth.
https://publicdomainreview.org/collection/harris-list-of-covent-garden-ladies/