Same answer as zeno98:
Zack0Wack0's Construct 2 Plugins
Im not 100% sure how it works, but i tried the following and it seemed to work :
1, start game, press 's' to save score. close game.
2, when i returned to the game the second time and pressed 'r' to retrieve and it loaded '25' for the score.
<img src="http://dl.dropbox.com/u/22173473/storage.png" border="0" />
i might be doing something wrong, not sure.