They are not my friends or family. These are normal people brought in through adwords PPC. Paid $500 , received 350 visits, 168 became simple members, 26 registered for a free trial, 19 autoenrolled for 70Usd/year, the rest canceled. For me this is relevant because I got my money back. I can pursue existing members to share and get me their friends in exchange of 1-2 months free. Would these numbers be relevant for an investor ? Should I keep on doing it and see if the numbers stack up or if it was a lucky streak?
My first question would be, have all your users paid the $70 upfront, or is there a chance that some of them might cancel and get refunds? In order to make sure your economics make sense, you need to take churn into account and it's not 100% clear to me whether this is the case.
Assuming that you do have churn under control (and therefore that your product does have a clear benefit that a fraction of your users are willing to pay for on a repeatable basis), my next step would be to assess market size. The spectrum ranges from 19 people (your current users) to 1b+. What you could do would be to try and run a slightly larger campaign and see if the numbers still add up, ideally spending no more than the proceeds of your previous campaign.
If things work out well, you might even make this a self-funded business, in which case you wouldn't even need to search for an investor ;-)