Hello @Ace2000
They changed pricing with version 2.8.
@duncan explained it in this thread, because I think many other users had the same question:
https://community.sparkleapp.com/t/sparkle-2-8-pricing/142
I felt a bit unsure myself. I had bought the Sparkle Pro license two years ago and was happy with the purchase.
But I decided to change it to the subscription in July this year because I felt I wanted to support the development of Sparkle.
As @FlaminFig mentioned, you can always get the Sparkle Pro subscription later.