Trouble upgrading sql server 2012 to 2017 - losing enterprise

Hi all

I am trying to upgrade my Microsoft SQL Server 2012 (SP3-CU1) Enterprise Edition to the 2017 version. I am using the setup wizard. However it auto-inputs the product code and when I click next I get the license for the 2017 standard edition and not the enterprise edition. Any idea how to solve this or am I just misunderstanding the license: 

>MICROSOFT SOFTWARE LICENSE TERMS

>MICROSOFT SQL SERVER 2017 STANDARD

I tried getting the product key with the Get-SqlServerKeys.psm1 script from technet and got a different key than what was input automatically in the install wizard. Tried using the key from the script instead but got an invalid key error.

Thanks in advance