About Sublime Text says that I have a Single User License registered. Is it going to prompt me to upgrade, or am I grandfathered in some way? I bought this Sublime 3 license in Feb 2018. Just trying to understand what's going on. The app itself is great so far, especially the GPU performance.
Your license is still valid for all versions released before Feb 2021 (3 years after purchase). Once you update to a version released after that date you will see a "LICENSE UPGRADE REQUIRED" in the title bar. Under `Help > Upgrade License` you can then purchase an upgrade. There is also a popup prompting for an upgrade if you've entered an "expired" license anew.
