Hello Wifi spot,
Your license should be valid for all companies that you create in a single instance.
Even if you create a new legal entity there should be no issue.
In case you want to double check, search for
www.google.de/url;rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwjR_7j3x6_hAhWMTRUIHaa2CYYQFjAAegQIARAC&url=https%3A%2F%2Fdownload.microsoft.com%2Fdownload%2F0%2FD%2F0%2F0D0CFCE8-75DA-4FF4-9207-7642B3E06877%2Fmicrosoft-dynamics-ax-2012-r3-licensing-guide.pdf&usg=AOvVaw25XlIOa8WrO4lrZzQ3uj2M
and take a look at the licensing guide.
Best regards,
Ludwig