I hope you meant backtest results, (which are stored permanently) and not results of exploration/scan as such aren't stored, (but you can write a simple code to do so)
Program Files\Amibroker\Reports
Assuming you installed AB inside Program files (program files could be program files (x86), depending upon your OS and AB version.
inside that folder, each folder reprents one backtest data.
also you will find the file called "results.rlst" which is the text file with all the data regarding all the backtests done. (very useful)