If your cashflow doesn't depend on these specific individuals, I would honestly at this point open up the firehouse and give them access to all features. The goal is to wow them into wanting to refer your product to other people. By limiting the features, you're lowering the chance you're going to wow them. I'm assuming the affiliate, by not paying, will be a drop in the bucket compared to the potential of what you'll get by having them showcase your product to other potential clients.
WpEngine example:
Now ideally here you are in a situation where you can have your cake and eat it too by showing all the features "vertically" but perhaps not "horizontally" what I mean by that is what wpengine does for their affiliates. They give one full environment (dev, staging prod) for free to any affiliate. However, as soon as I make a website for a client, I'll need to purchase an incremental license to host their website. So I can 1 for free as my sandbox/to showcase, or heck even to "cheat" and get 1 website free, but after that I'm having to pay. However, I don't feel like they're "limiting" my features I get to explore by doing things this way.
Above vertically means I get to see all the features, but I can't expand horizontally for free (I have to pay to add on additional clients)