A secure license key solution provides software license keys for enabling and/or tracing use of software where a license key comprises a message encrypted by a private key and the public key for verifying the message according to asymmetric encryption techniques. The message and public key may be used by a software enabler (e.g. an installation wizard) to enable the software and/or create a secure tag for incorporating with an output of the software to uniquely the license of the software used to create the output. A license key management system may generate license keys for respective software licensees and comprise a database to store an association between respective software licensees and their license keys to identify the license associated with output obtained.