I just installed new license files / new GPOs. Should I keep or delete the old license files / GPOs?

You do not need to keep every license GPO around that is created by LT.

You can delete old/ expired licensing GPOs, as well as anything else you do not need found in this screen:

275_1_lt-faq-111

You have two options:

Option 1 — One GPO per component license, the latest license you have.
Option 2 — A single GPO with the latest component licenses you have.

See How to install UNIVERSAL licenses for NEW Customers (via GPO, SCCM or MDM) for instructions on how to install your new license.

See Using LT for license cleanup for additional information on how to use our LT to help you do a Deep search for licenses and help you automatically clean up