Pro Tools 12.3.1 is a full installer (not an updater that requires a previous version installed).See the Support section of for assistance with iLok License Manager, your iLok account, etc.Review the licenses on your iLok at or in iLok License Manager.The bonus plug-ins (introduced with v12.2) use a Pro Tools Plan or Pro Tools HD Plan license.Pro Tools HD 12.3.1 software requires both Pro Tools 12 and Pro Tools HD 12 iLok authorizations (licenses) to run.This can be a single license or in a bundle.
Pro Tools 12.3.1 Read Me - Windows (PDF).Please review the following documents for important compatibility information, known issues, error messages, issues resolved, etc.