I don't see where this question had come up on this forum and I cannot find clear documentation on any JBoss page concerning this. Can Wildfly be deployed and used in a production environment? Are there licensing fees to be paid to use Wildfly in production (non development) environments?
Wildfly is opensource and free to use in production. JBoss EAP is a productized wildfly with additional patches and support, in this case you should buy support to use EAP in production, however JBoss EAP is free for development mode.