Sublime never offered lifetime subscriptions. web.archive.org/web/20150928064400/…/sales_faq You can even see as far back as 2014 that if you purchased Sublime Text 2 when Sublime 3 was still in beta:

• Upgrade Policy
  A license is valid for Sublime Text 3, and includes all point updates, as well as access to prior versions (e.g., Sublime Text 2). Future major versions, such as Sublime Text 4, will be a paid upgrade.
• Expiration Date
  Licenses purchased for Sublime Text 3 do not expire, however an upgrade fee will be required for Sublime Text 4.

You can find that disagreeable, but it was not something they hid from us customers.