How to reproduce:
1. Open any project on 2019.3.0a12

Expected result: the project opens up
Actual result: the project is not created, error thrown "No valid Unity Editor license found. Please contact your administrator."

Reproducible with: 2019.3.0a12
Not reproducible with: 2017.4.32f1, 2018.4.7f1, 2019.2.2f1, 2019.3.0a11

Fixed in 2019.3.0a13

Workaround:
Create/update the file C:\ProgramData\Unity\config\services-config.json file and write the following lines
{
"enableEntitlementLicensing": false
}