Ask HN: What to ask after advising a startup that start to pick steam

Going anonymous for this one: for the past 20 months, I have been helping/advising a startup on what to focus on for their mobile apps (especially for iOS), and because of my personal network with some Apple App Store folks, their app is now getting noticed and climbing the chart: taking over some well known apps in their category. I was introduced to the CEO through a common friend, and I didn’t mind advising the startup’s CEO for free: advices did include some technical solution to solve some issues they were facing, recommendations on some features the app should be pushing forward, etc. A few months back, the CEO reached out since they had a major issue and their app failed the App Store submission; after spending an hour on the phone and advising what should be done, and using some personal connections to understand why the Review was really rejected, they got the next version approved in a couple hours: the previous rejection had their app rejected for over 5 weeks and they were going nowhere. Over the 20 months period, I did meet with the CEO a few times, and had at least monthly discussions with him through email or phone call. I have never asked anything in return, but now that the app start to get more users and climbing the chart, I am thinking it maybe time to discuss a deal; especially since the CEO reached again out to me earlier today to let me know how well their app was doing. After a quick congratulations he is asking me now more advices, and would like to access more of my personal network to take the app to the next level. Any advice / suggestions appreciated; I have myself already a full time job (which I like), so not considering to join the startup. My background is mostly on the engineering side, but after working years with product manager and marketing folks especially in the iOS ecosystem I have picked up some good knowledge.