According to MakeMusic, Finale 2012 is not supported in 10.4 (Mojave) and there could be problems. Only Finale 25 and 26 are officially supported.

Authorizations can normally be added or removed in the Help menu.

You can log into your MakeMusic account and manage authorizations as well. There is no guarantee of success.

On my new iMac, my copies of 2014.5 and PM 2014.5 work (with the usual limitations) in Demo mode. When I tried to authorize them, both crash big time while trying to verify the serial number. While examining the crash logs, I determined that it wasn’t worth it for me to resolve the conflict even if i could.

If you’re successful, that will be interesting to know. 2011 was incompatible with High Sierra and I skipped 2012.

In case you missed the recent announcement:

MakeMusic is offering Finale on sale for a limited time, through May 20, 2019. New users of Finale can purchase it for $249, a significant savings off of the $600 regular price. However, if you already own a competing product, I recommend that you contact MakeMusic to obtain a quote for a competitive upgrade, which could be less expensive. MakeMusic has removed this option from their store, but the latest information is that it is still being offered by request.

For existing users on Finale v25 or earlier, the sale price for an upgrade to v26 is $99 (regular $149). Both sales items require the code FINALE261 at checkout.

Hi, some follow-up:  I hadn't realized I could access Authorizations through Finale's Help menu (see first comment above). Going that route I was able to authorize my antiq

...my antique Finale 2012 on my shiny new iMac running OS 10.14.4. I've noticed one or two minor things in Speedy Entry which don't work quite as expected, but on the whole it's working just fine.

Human Playback will probably crash your Mac and certain functions in Expression Shapes. If the workarounds... uh... work, then good.