If you need to use Radmin Server 3.5.2 legitimately, here are your proper options:
There are several ways to obtain a license code for Radmin Server 3.5.2:
Because Famatech no longer officially sells new licenses for 3.5.2 (they now focus on Radmin 3.5.2x and Radmin VPN), users feel stuck. Consequently, the internet is flooded with websites claiming to offer free "license codes," "keygens," or "activation patches" for this specific build.