According to the CB13 manual, you can activate the program on a maximum of two computers with one serial number.
Download the manual here: http://download.chessbase.com/Download/cb13/ChessBase13Manual_eng.pdf
See page 11.
Edit: This doesn't really answer your question but at least you know you can have it on both machines. The program will need to be activated to access the cloud.
currently have Chessbase 12, am thinking about upgrading to Chessbase 13, mostly for the cloud database storage. any idea how many machine licenses come with ChessBase 13? would be great to use the cloud feature and have chessbase on my powerful desktop PC and also my surface pro 3. i searched their site and google, but can't find an answer.