1. Run ADSI Edit tool: adsi.msc
2. Connect to
3. In connection settings Select a well known Naming Context – Configuration
4. Expand Configuration – Services – Microsoft Exchange – <Name of your Organization> – Administrative Groups – Exchange Administrative Group (FYDIBOHF23SPDLT) – Servers
5. Click Exchange server Properties
6. Clear msExchProductID attribute
7. Restart Microsoft Exchange Information Store service if server holds mailbox role
8. Enter New Product Key using Exchange Management Console or PowerShell
Set-ExchangeServer -Identity Server1 -ProductKey xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
9. Restart Microsoft Exchange Information Store service
Здесь описано, как понизить лицензию на сервере с ролью Edge Transport:
https://okrylov.wordpress.com/2016/11/07/downgrade-exchange-server-edition/