The Diablo III Website explains that to combat fraud, as of the new version, digitally purchased editions of Diablo III will be quarantined as the Starter Edition for up to 72 hours (thanks GameSpot). Here's word:

As of patch 1.0.3, when purchasing a digital version of Diablo III through the online store or your Battle.net Account, players are restricted to the Starter Edition for the first 72 hours (sometimes less). Players on Starter Editions have the following restrictions:

        • Act I up to the Skeleton King is available
        • Level 13 cap
        • Matchmaking available only with other Starter Edition players
        • No Auction House access (Real Money or Gold)
        • Global Play is not available. Players attempting to connect to Diablo III Starter Edition in a region other than their Battle.net Account's home region will receive Error 12. See the Global Play support article for more information.

More information regarding the Starter Edition is available here:
http://us.battle.net/support/en/article/diablo-iii-starter-edition-guest-pass

If you are still encountering the Starter Edition restrictions over 72 hours past the date of purchase, please let Customer Service know: http://us.battle.net/support/en/article/contact