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.
PMDG’s EULA originally prohibited license transfers, but in recent years, they have offered a License Transfer System. fsx pmdg 737 ngx activation code
If you're experiencing specific issues or need detailed steps for your particular situation, consider reaching out to PMDG Simulations' support directly or looking through their official documentation and forums for more detailed instructions. Upon purchasing, you should receive an activation code