For anyone else wondering how to accomplish this, I found the steps in this Licensing Guide from Microsoft.
"To take advantage of Dual Use rights, a Dynamics 365 Business Central cloud subscription needs to be activated via CSP. Once the subscription has been activated, a customer account will be created in PartnerSource Business Center (PSBC) with the equivalent user SLs. The customer can access their onpremises/dual use rights license key (flf. format) by signing in to CustomerSource, selecting the ‘My Products and Services’ link from the dropdown menu and then clicking on the ‘Registration Keys’ link beside the Microsoft Dynamics 365 Business Central product."
1) Sign in to CustomerSource
2) Click on your Name at the top right and select "Products & Services Summary"
3) Under Registered Products click the link for "Please contact your partner for Keys"
4) Answer the questions in the dropdowns
5) Click Display License Keys
6) Download the License Keys in .flf format
7) Open Nav Container Helper and use the Import-NavContainerLicense to point the container at the license file.