How can i update version of prince if i'm buy license? Now i have 11 i need 12, how can i do that?

If your license was purchased recently then it may already work with Prince 12, you can check the support period. Alternatively, you may need to purchase a support contract.

License was purchased more than year ago, but now we need new version, because old vesion have some problem with css styles for header. Can we upgrade prince?