Once you have a bona fide license, here is the activation process for FSX:
Upon purchasing, you should receive an activation code. This could be via email or provided during the purchase process if it's a digital sale. Keep this code safe as you will need it for activation. fsx pmdg 737 ngx activation code
One of the biggest points of confusion for new PMDG users is where the activation details actually live. Once you have a bona fide license, here
PMDG’s EULA originally prohibited license transfers, but in recent years, they have offered a License Transfer System. PMDG’s EULA originally prohibited license transfers