Code 300016 after starter (Atc 1 chapter 3)

I finished the starter (Act 1 chapter 3) I want to continue by inproving my character. I can see error 300016. When I try to continue I start the game from the beginning!!!

Level 13 or Skeleton King is the end of Starter Edition (trial version).
If you want to continue, you need to purchase the game. Currently, the in-game purchase screen might through this error due to some bug.
If you want to purchase the game, you may do it via Blizzard’s shop web page.

If you have already purchased the game, remember to redeem the game key (authentication key) on the launcher or on your account management web page. The key should be printed on a label sticked on the booklet or DVD envelope for physical retail copy.

Once you redeem the key, the progress may be reset to beginning but you can change it on the game settings menu (under the Resume Game button). Just redo the last quest to continue the game.