Hello,
By default game saves are stored and accessed by any game version from the same location (no need to export import, they should appear in both demo and full game at loading slots popup). It is possible to export and import the saves from demo, however i would highly recommend replaying (since a lot of scenes where skipped, and the latest version's unlocks weren't granted in demo).
Game Saves folder (in case you're using different machines) : "C:\Users\[YOUR WINDOWS USER NAME]\AppData\LocalLow"
Cheers,
~NK