If he left during a session without an explanation or saying goodbye, the likelihood is he came whether he had permission or not and didn't think about your feelings and will probably come crawling back when he feels horny again. Either that or he just wasn't enjoying it and didn't have the courtesy to tell you.
If you are just starting out it will take time to discover what you like and what you don't and you need to have honest conversations with your sub, talk about what's going well, what isn't, if there's something either of you would like to try. And don't always make it sexual, get to know each other.
That would be my bit of advice, I used to be the guy that came on this site when horny, looking for a quick fix, being really selfish and not thinking about anyone else. It took me a while to meet someone I click with, I now have an awesome Miss, we don't get to have sessions all the time due to us both leading busy lives but we chat most days, even if just a couple of messages. She has made me a much better sub, she pushes me without demanding I break limits, I have done things I never thought I would but always wanted to.
So just hang in there, stay true to yourself and the right sub will come along, the main thing is you need to be happy.
