If something is lasting, it sticks around for a very long time. If you and your best pal have known each other since you were three, that's a lasting friendship.
Remember that time when you wore a purple plaid shirt, a green tutu, and a top hat to school? You certainly made a lasting impression! And while using donation money to throw a fabulous party might be fun in the short term, spending the cash on new books for the school library will have more of a lasting impact. This adjective is great for things that last or continue for a long, long time.