The license key for Auslogics Disk Defragmenter 2.11 Pro can be purchased from the official Auslogics website or from authorized resellers. The cost of a single license key is around $39.95.

The final versions of iDefrag (around v5, not 2.x.x) were designed for older Mac OS versions (HFS+ drives) and are generally incompatible with modern macOS (macOS 11 Big Sur and later) and APFS-formatted drives. SSD Warning: strongly recommended not to defragment SSDs

: iDefrag was designed for HFS+ formatted drives; it does not support the newer APFS file system used in modern macOS versions. Modern Systems

For drive management on modern Macs, users are directed to use Apple's Disk Utility