Depends on your spiritual director. Some ask for payment, some do not. There are a number of priests and religious who have received extensive training in spiritual direction, do it as a full-time ministry, and rely on the payment they receive from directees for their upkeep. Seems fair to me. Others offer the ministry for free because their income comes from other sources. Such persons tend not to do this as a full-time ministry and may or may not have received specialized training.
Just for background, my last spiritual director was a woman religious who had years of experience in spiritual direction, had received specialized training in it, and who did it pretty much full time. I paid her for each session. On the other hand, I also served as a spiritual director after receiving training, but did so only a few hours a week, and relied on other sources for my income. I did not charge for spiritual direction.
It’s perfectly acceptable to ask your director if payment is expected and how much that payment should be.
