Depending on the level of DRM you’re after password protected clusters might not be the most suitable, for example this post which uses reflection to change the cluster password (not verified, just from a quick search). IIRC there was some discussion/warning about not expecting high security from clusters when passwords were first introduced.
That said, a ‘lazy’ way of doing the licensing would be to write a simple ‘gate’ component which passes data through if the license is valid, and passes nulls to ‘break’ the definition if the license is invalid.
There are lots of ways to do licensing, but the quickest way I can think of would be to include a hashed/encoded text file in the same folder as the GH definition which is referenced by the ‘gate’. If you want to license for a specific machine, you could create a hash based on some combination of the MAC address and expiry date. Lots of plugins have done this in some capacity in the early stages of development - where the client generates a request code which is really just some version of the MAC address, and then you provide a license specifically for that request code and any other data you want to embed. Typically this would be done through a .reg file to simplify installation of the license.