Paying for the service they use would suit most users I suspect. Subscription is preferable for developers.
Why is a subscription preferable to developers?
I imagine that a transaction fee model would incentivize developers to encourage more volume vs just saving.
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Why is a subscription preferable to developers?
Consistent revenue.
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The same reason any subscription model proves popular; regular, predictable income. @theBTCmanual certainly has the right idea about combining though.
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