As of SAP NetWeaver 2004s after the system has been installed, an 18 digit system number and a 10 digit installation number is assigned with the value “0”. When you receive your permanent license key from SAP, you will also be assigned the system and installation numbers, which are loaded from the license key file.
If you create a temporary license key later, both numbers are copied to it. To change the numbers you first have to delete all the existing license keys and then import the new license key with the correct numbers. If you unintentionally import a license key with an “incorrect” system or installation number, you will get an error message.