This seems like a neat product, but it’s better for me as a user to pay some amount once than 4/month forever. I want to encourage you to keep building the software, but have to keep my list of monthlies really small.
If no, then a big chunk of your installbase is going to be insecure. Some people might feel that's unethical, or too much of a bad press worry.
If yes, then you need to patch a growing number of branches with libaries that might make breaking changes requiring re-writes in your code.
I guess Microsoft ran into this problem when the End Of Lifed windows XP.
That said, for someone who just has an app they are writing and wants to make a little money, it's probably overthinking.
We are thinking about offering a lifetime membership plan, but need to figure out the details first. How much would you be willing to pay for a lifetime licence?
First year, it's $5/month. Second, it's $4. Third year, it's $3. And so on. Ideally it's free year 6 and from then on as long as you have an active account. But it could be $1/year.
I already have enough things I have to pay for every month for the rest of my life.
You need recurrent money to run the business. It comes from ads/tracking/data and/or from subscriptions. Some business want to protect your privacy by not tracking you or serve you ads, so you should expect a non zero recurrent cost.
It can be extremely small, but it needs to be there to be profitable: the business has to cover its costs somehow, or it won't last.
> I already have enough things I have to pay for every month for the rest of my life.
So does this business to provide a service to you, for as long as you remain a customer.