The educational edition of Sigasi is free to use. In exchange for this, we ask that you enable Talkback and that you keep your software up to date. Any version that is more than 6 months old will stop working. We do this to ensure that everybody gets the latest features, and keep people from running into any issues that have already been fixed.
This information only applies to Educational licenses.
If you have a commercial license, you can keep using older versions.