The thing you have to remember is that there are thousands of products out there all trying to charge a subscription, and most people aren't going to justify taking on more than a very small handful of them at any time. Plus (not directed at you specifically, just in general), your product almost certainly isn't as good or as important to the customer as you think it is unless you've genuinely identified some niche nobody else is operating in, of you have an exceptionally polished product with few competitors.

People are however consistently willing to regularly make one-off purchases to get something they can "own". I've bought way more lifetime licenses for software than I've taken out subscriptions. When you consider that nobody stays subscribed for life, there's always a number that you can charge for lifetime which is in fact functionally equivalent to a subscription anyway.