Duittuit,
You want to use the passkey - if you don't, you don't get the bonus early completion.
Perhaps more interestingly, we have introduced a new Quick Return Bonus (QRB) points program, which will be tied to passkeys.
Do I need to get a passkey?
No, you can leave it blank during configuration and the client will operate normally. But we will not have any way of distinguishing work units you completed from the work units others with the same name have completed. And you will not be eligible for the new bonus points program, currently available in the SMP2 client.
http://folding.stanford.edu/English/FAQ-passkey
Just my 2-cents worth.
Sun :-)