What does "Help→Release Licenses Everywhere" do? And why would I use it?

Pressing this will release all your licenses from any computer that you have used your licenses on before.

This is useful if you have have used your personal licenses in a studio for a contract but forgot to sign out when you left. Pressing this will make sure that the next time the version of Cinema 4D that had your licenses is used, it will delete your login details from that machine and free up all your licenses.