This posting is older than 6 months and can contain outdated information.
TL;DR:
This has *zero* to do with DRM. You're seeing one instance of an OS X-wide, completely DRM-unrelated effect of your Ethernet adapter being broken and your Mac system assuming a new host identity in response.
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1) Remote Buddy does not use DRM. It uses a license code.
2) To protect against piracy, that license code needs to be verified online once.
3) The license code and verification result is then saved as a host-specific setting using the OS X preferences system (which stores it in ~/Library/Preferences/ByHost/com.iospirit.remotebuddy.license.[OS X HOST ID].plist)
4) That [OS X HOST ID] is derived from your primary network interface, which - for the Mac Mini - is the Ethernet adapter.
5) If a Mac mini suffers from a defective Ethernet controller, another network interface (WiFi, Firewire, Thunderbolt, ..) will take its place.
6) Since that new network interface will have a different MAC address, OS X will create and use another [OS X HOST ID]. Yes, that Mac just got a brand-new identity!
7) As a consequence, a lot of system and application settings reset to default values since - from the point of view of OS X - there no longer are any host-specific settings for the system with that new [OS X HOST ID].
8) Due to the new [OS X HOST ID], when Remote Buddy asks OS X for the license code settings, OS X replies that there are no such settings.
9) Without a license code, Remote Buddy asks you to enter it.
Solution:
Re-enter the license code and let OS X save it for your Mac's new [OS X HOST ID].
- Felix
P.S.: Regarding "thanx as once again $#@% DRM only screws those who paid": I tried to look up your license info to send it to you in response, but couldn't do so, because you don't seem to have purchased anything from IOSPIRIT, yet.