Software updates will be free always, whether you are on lifetime or annual plans. We have no plan to breakout pricing a la carte either. Your membership includes everything you see now, and going forward.
The only exception to the above might be where we have an offering that requires a license fee to a third party. For example, if we had offered a DSP solution that required a large license to a third party, then if it was deemed important enough to include into Roon, we might make it an in-app purchase. We have no plans to do things like that at the moment, but just giving this as an example of our thinking.
If you want to support us further after buying a lifetime membership, you can buy your friends the gift of Roon 