If Yay is (are?) attempting to establish a rapport, they aren't doing a very good job.
Just asking, like Elliot said, should be enough - rather than trying to turn everything into a transaction.
Is there a certain emotional immaturity in Yay? Something that reduces other people to commodities or consumables in order to "get things" that Yay wants? Or is simply asking (and therefore putting themselves in someone else's debt) something Yay is too proud to do?
I believe there is definitely emotional immaturity. It fits in with what we've seen of their behaviour earlier - they don't really know how to establish a normal relationship with another person; witness their attempts to make friends with Roko. But consider their history. They started out in some sort of extremely covert role where they didn't interact with people at all as far as they could help it. When they broke cover they started out in "tell everyone to do because we're ultra-powerful" mode (the Bubbles / Corpse Witch saga). Toddlers also act this way, except because they're very self-centred (so that their orders are mostly along the lines of "give me <x>") and not ultra-powerful, they often throw tantrums if you tell them "no", whereas Yay would more likely just electro-stun you.
Yay found the experience of interacting with people to be an intriguing one, I suppose, and so now they're trying to imitate the way normal people interact, but they're definitely not very good at it yet. Their desperation to get Roko to like them is quite reminiscent of many young kids who want to be friends with someone. (Quite how Yay decided that Roko was the "cool kid" they wanted to be friends with, I don't know.) Now they're trying to make friends with Elliot but they still haven't figured out how normal people do it. The transactional approach is probably a remnant - I suspect that after the Corpse Witch arc, Yay was somewhat perplexed that everyone didn't suddenly like them, since Yay had done them all a series of quite large favours. They tried this again with Roko (giving away $2 billion to charity) and it didn't work the way they expected it to then, either. They've scaled it down this time, possibly because of Roko's reaction, and it's
still not working they way they wanted it to.
This approach is fundamentally an emotionally immature one - trying to buy feelings implicitly treats the other person's emotions as less important than your own. The mature approach, instead of trying to
make people like you, is to give them the
opportunity to like you, but respecting thir right to make their own decision about that. My youngest daughter took a long time to accept that she couldn't just expect her older siblings to be available to play with her any time she wanted, and even longer to accept that just because they didn't want to play with her right now, it doesn't mean that they don't like her at all.
True friendship grows out of equal standing, and it's probably going to take Yay a while to get the hang of treating other people as having equal dignity and autonomy, when for so long they've viewed everyone else as inferiors. But they're smart and they're making progress; I'm sure they'll figure it out.