I have seen it demands Krita 9.9 EUR using Microsoft store. Is this one-time purchase?
Where is an updated version for Krita KDE as I have Krita KDE 4.1.7.

Hi Toplisek,

yes it is an one time purchase, you get the convenience of updates from the store with it.
If by Krita KDE you mean Krita on Linux, the packages are provided by your linux distributions they will be updated when the distributions provide update. However if you want latest versions on linux you can download the appimages from the krita website

Yes it is. You can always download it for free on krita.org. The microsoft store version is for people who want easy updates and the money goes directly to development.