I am recently Re-reading EoTW and i came accross at the end of chapeter 7 when Rand askes moiraine for help with his sick dad. He says "i'll pay any price in my power if you help him. Anything."

and Moiraine says "We wil speak of prices later, rand, if at all"

so i dont remember if she asked him to do something in repayment for her help with his father.

And if not then if/when she returns what may she ask for? 

 

 

 

No and no.

"if at all" .... so that's the case, no price.

Leaving with her from the town would be payment enough.

 

I am betting that she has yet to bring it up. Mostly because Aes Sedai are tricky like that. Though she may not (IIRC) she swore to stop manipulating him.