For one thing, ASE lets you do a helluva lot in the trial version. All you have to do is click the "No, I'm going to be a bastard for at least a little longer" button every week and you get access to everything except a few features in the player searching and slower refreshing of the scanner.
For another thing, you only have to dish out $10 for a whole goddam year with not only no nag screens, but the abilities to search player names in tons of games, scan and ping hundreds of servers in mere seconds, and maintain a buddy list of all your friends and where they're playing!