That doesn't require a subscription. Plenty of companies offer a permanent purchase that comes with a year of updates or all minor-version updates or similar.
The option is there to treat it similarly to a subscription, but importantly you never have to pay and what you already own can never be changed or taken away.
- A year of support on our forums (real company-provided support, not just peer-provided).
- All minor releases and bug-fix builds within the year.
- After the subscription has expired, you still keep everything that you purchased forever, including being able to download anything you own at any time (we keep track of all of that for you).
We do have some "catches" to prevent free-riders at the expense of customers that maintain subscriptions, notably that you can only renew a subscription at the normal price within 2 years of your last renewal. After that, we start to ratchet up the renewal costs until, at the 5-year mark, you'll need to (effectively) purchase a new license.
Also, we offer inexpensive direct phone/email support through a separate "support session" method that is not tied to your subscription. So, even after a subscription expires, you still have direct support options.
The key is that any arrangement be fair and beneficial to both parties. In our case, we get a steady, predictable stream of revenue, and the customers get support, enhancements, and bug fixes quicker and at less cost.