I see you edited your original comment since last time, so I can augment my answer.
I could definitely include a lifetime purchase option for a certain price, but I was skeptical whether people would actually be interested in something like that, mainly due to the potential price difference. I honestly thought that the current model would be better received by potential customers as it is more a pay only what you use model while also keeping access. I did not expect that anyone would actually be interested in a lifetime license. But to be fair, the payment model was designed back when the application was in an earlier development stage and didn’t even work properly for like 50% of users.
I will definitely rework the website to better get the point across on how continuous updates are handled as there is no intention to make it a predatory model. Then I will reevaluate the licensing model.