Maybe, we don't know. We won't ever charge for the
current version.
But if we do a rewrite (which we'd like to at some point) we might release a basic free version and a feature-added pay-for version. We do write software for a living, after all.
However if we do end up charging it won't be much - less than $100, perhaps considerably less than that. Best to use a product if its features suit you rather than worry about the cost, if the cost is relatively neglible. One person's time wasted for one or two hours will cost you more ...
I am really curious about this. If it does, we will not use it currently.