A new model for electronic software distribution and copyright protection based on an asymmetric public-key traitor tracing scheme is designed. Buyers can download software freely from Internet , but they can't run it without E-license. If software is copied and redistributed illegally, a merchant can trace back to its original owner using tracing algorithm once the electronic license and personal key are found. The model offers full frame proof, non-repudiation and can guarantee the right of both merchant and buyers.