if i play the demo, will i be able to transfer my save to the full version?
Yes. Both the full game and the demo version share the same save files. The full version should start off right where you left your last save.
But here's where the saves are stored: C:\Users\*yourUserName*\AppData\LocalLow\SilverTabbyCat\Trials of Harmony\Saves in case you want to mess with them directly.
Have fun and stay awesome