You will get free updates to Sytist for the first year. After that you can pay for another year of updates for $99. But you don't have to pay right after a year.
How does this work?
Lets say an update comes out 14 months after you purchase but you don't see anything that would benefit you so you don't need to update and don't need to pay anything. A few months later another update comes out and you see some new features you like. You can then pay the update fee and that fee will cover that update and any updates that come out for the following 12 months.
How often do updates come out?
There is not a set timeline for updates, but they average every 2-3 months.
Do I have to update?
No. You don't have to update for your Sytist to continue working.