The important thing is to run the activate.exe file during the 24 hour period.
Actually, I think they also tweak the installer itself to "phone home" to check that the offer is still active.
Regarding the app itself, I dislike the "toilet paper" model.
I have been using Surfulater, but I've been having problems with the files corrupting when syncing with my flash drive (a single database is composed of multiple files, and if I forget to close the app, they don't all copy, so they get out of sync).
Evernote, on the other hand, appears to have its own built-in sync feature.
It built in OCR looks pretty cool (I think that's been mentioned around here before).
Support for Google desktop search is cool, but I use Copernic.