You just need to plan how that business model works and know that you won't have recurring revenue. Maybe that means you build companion apps, offer an optional subscription tier (often its cloud storage/device sharing based) or something like that.
I've thought of doing a subscription like service but its use case is more of a once-in-a-while style so an option there would be pay-per use instead of a subscription.
You could also copy many WordPress plugins, which charge a fee for the first year (which includes support and updates) but then expires afterward. So they can continue using the plugin but won’t get any new updates/support.
However the business is as it is
For software I really like the patreon model (like in some game communities) monthly subscription you could cancel after downloading and if you want updates you just get another month. Big portion will just pay monthly while they wait anyway. Best for all worlds.
Otherwise I would maybe recommend a yearly price instead of monthly. Especially if the monthly would be something small anyway. Easy to forget so most people will at least pay 2 years and you save a lot in transaction costs.
I run a SaaS that relies on one time payment. The income currently covers all the expenses, and leaves me some nice pocket money.
Is this model for everyone? No. The unique proposition of my service is actually the one time payment aspect. Does everything should be subscription? No. I avoid subscriptions as much as possible, unless there is a cost involved in running the service.
So YMMV. I wouldn’t pay a subscription for a MacOS app, unless there is an ongoing operational cost for the developer.
Feel free to email me (profile -> website) if you want to chat.
Additionally, there is a distinction between single and ongoing payment in the context of usability. Specifically, it makes little sense to sell a calculator program via a subscription fee but you also reach a limit of the possible customer base. Just like mobile applications. With subscription, you can keep milking the same customer for money indefinitely, but in such case you have to keep providing some services that is worth the payment.
Another thought, maybe your app has the potential to be extended, you can make extensions available as addons for a fee.
One time payments are fine when you are in a growing market like iOS in 2009. The only long time successful Mac Indy app that I can think of without a subscription is BBedit which has been around since 1990 and made every transition along with Apple.
Sheesh.
You can have one-time licenses but updates require another license (ie: discounted). It is the same model of SaaS but with a different payment plan.
Unlimited/lifetime licenses are a way to either deliver a really bad product or create an unsustainable company.