PLA sticks to plexiglass print bed. What do I do to prevent it?

[snoozer]

A friend just loaned me his never-used, 5-year-old, Monoprice Architect 3D printer. No joke; never set up or used.

So I set it up and printed a test object. All went well except the object stuck to the plexiglass bed. I was able to remove it with a hair dryer but really don't want to have this occur again.

Is there a way to keep the object from sticking so strongly? My friend gave me a can of hairspray with the printer. Is that to serve as a separating medium? Or should I use the sheet of 3M material (also included) that will stick to the bed itself? I'm not sure exactly what the 3M material is but it's a perfect fit for the bed size and probably is for that purpose. I just don't know for sure and don't want to trash the printer before I give it back.

Thanks to all!