You can also be on ebay at the same time if you wish. AS will send your snipe if you are logged on your computer or not, no matter what you are doing. I have actually monitored an auction on ebay, just watching and waiting for my snipe to hit. It was fun to watch others bidding and losing in the last few seconds when AS sent my snipe bid automatically!!
So go on do whatever you choose to do. Be on the computer or off, on ebay or off. AS will do exactly what you have asked it do for you.