Dave,
Thanks for sharing your thoughts and issues about your continued development of HanDBase. I wonder if a three-pronged approach would be financially successful as well as appealing to a wider market?
First, I would still prefer an option of an outright purchase of a specific version. That should allow me to continue to use that version indefinitely as long as I was satisfied with its features (and bugs) [and as long as a change in the underlying operating system did not break it <groan>].
Second, I believe many would be willing to pay a subscription fee to subsidize new developments if that meant an option of early access to beta versions and/or early access and a reduced price for the final new version. I think it would be reasonable for these beta versions to have a "sunset" feature either to cause them to no longer work after some period of time during which a new replacement beta was likely to be provided, and/or would cause them to no longer work if the subscription lapsed.
Third, I think any significant upgrade, especially which included a new/enhanced feature, should require purchase. There might be a discounted price for an upgrade to the immediately prior version, but full price otherwise. [As I have mentioned previously, I think the price for your product is too low based on the features and functionality it provides.]
Finally, you also might consider providing a way for individuals to simply donate to your development efforts as a way to express their satisfaction of your product along with posting wishes for new/enhanced features. I would guess that the number of such people is greater than zero.
Another satisfied user since back in the Palm days,