Suggestions on offering a Free Trial (Virtual Product)?

Hello, I sell Instagram Followers, YouTube Views/Likes, all that. On my site I am offering free trials for certain services, using an api plugin, that automatically sends to the panel. Through WooCommerce I have the product set to $0, I keep having users that keep abusing the free trial and keep using fake emails or the same email to get the free trials over and over.

Any suggestions on how to limit the customer or ip address to only be allowed to do the trial 1 time?
A membership plugin/what type of setup may help?
I don't think a content locker would help much..

I've been manually submitting all of the trials and I know which ones have submitted more then once, but with it being automated now (easier for me) I'm having users submit over and over..

Any suggestions is appreciated! Thank you

verify each order manually, and limit one order per user. use FB/gGoogleforum name to authenticate