PokerTracker

I consider to run few PT3 instances from different computers, which will be connected to the one central DB.
Does PokerTracker support parallel (Automatic) Import from few computers to the same databases? Should I expect some issues with it?

You should not import to the same database from multiple PT3s at the same time as this can cause corruption. As long as you import at different times that will work fine.

Thanks for the answer.
To be honest, I had a hope for a different answer
Is it a way to temporary lock a database?

Not that I'm aware of - even if there was that would prevent you accessing it from instance of PokerTracker.