First, let me start by saying I actually really appreciate this question and I hope my answer gives you faith in our long-term sustainability, exactly as you mention in the title of this thread.
The lifetime license model is appropriate for a very particular type of customer with very specific priorities:
Bring your own hardware
Doesn't want an ongoing subscription
Will mostly support themselves
It was the appropriate model to launch with as well because it allowed us to inject a larger cash infusion at the start. However, we see multiple additional revenue streams available to us in the future:
Subscription-based licensing. A lower price of entry for customers that aren't ready to make the lifetime commitment.
Support. A more premium support model that can help you on a 1:1 basis when you have issues with your server.
Cloud-based Services. Things like cloud backups (as an alternative or in addition to buddy backup). There are other cloud-assisted services such as reverse-proxy/relay that may warrant a subscription as well.
Hardware products We will never force anyone to buy a specific hardware product to use HexOS, but we may offer some for those that don't want to build their own in the future.
We actually have a few other ideas for additional offerings as well that would add additional revenue streams to Eshtek, but those are a little premature to discuss at this point. Bottom line: we don't just have a product plan, we have a full business plan for the future of this company and it has been designed to ensure a few key things:
We don't run out of cash.
We don't have to take on outside investors.
We can remain true to our mission and vision.
I hope this answers your question and gives you more confidence in our plans for the future. And if you have any other questions, don't hesitate to ask!