Last year Sonar started "subscription" ownership with monthly updates ("rolling updates") that included fixes and enhancements. However, the user owned Sonar even if they discontinued their subscription (it is $99 per year)unlike many subscriptions where the user does not own the product if they discontinue subscriptions.
Here is the announcement that I got in an e-mail:
You spoke, we listened, and now when you purchase SONAR Platinum (with Lifetime Updates), you’ll receive updates to all future versions of SONAR. You read that right. Purchase SONAR Platinum (with Lifetime Updates), and enjoy benefits like: •No more paying for fixes, workflow enhancements, and core feature updates
•Always have access to the latest version of SONAR
•Continue to enjoy our Rolling Updates