99% of “Radmin license check bypass” tools on torrent sites are Trojanized. Attackers embed backdoors into cracked Radmin installers, giving them access to your entire network. You bypass the license check only to invite ransomware.
You may have entered an incorrect key, or the key is meant for a different version of Radmin (e.g., trying to use a Radmin 2 key on Radmin 3). radmin license check