All progress can be transferred to the main game. Manually.
After the release, you will need to copy SaveGame.bin from
C:\Users\<username>\AppData\LocalLow\Pavel Kutejnikov\Tzakol In Exile Demo\
to
C:\Users\<username>\AppData\LocalLow\Pavel Kutejnikov\Tzakol In Exile\
Such a message will be in the menu.