it does when you authorize a new computer. But apple makes it incredibly east to migrate your data either from old computer to new or from time machine backup.

it does when you authorize a new computer. But apple makes it incredibly east to migrate your data either from old computer to new or from time machine backup. And I wouldn't be surprised if it synced iTunes authorization keys to .mac Even if Apple shuts down the iTunes store I expect them to keep up the authorization server as long as possible.