I purchased a lifetime Roon license, and have been running the core on a QNAP NAS since the beginning. No major issues, though I would prefer that for lifetime suscribers Roon would not require periodic revalidation of the license over the web.
Roon ARC is another story. This has been buggy and crash-prone and has required repeated deletion and reinstallation of the iphone app. However ARC has recently stabililized and seems to work much better than before.