No serial number is required. You simply sign in to the Creative Cloud Desktop app with your Adobe ID to activate your license [17, 22].
These now use a 3-year term license that expires after three years and does not require a recurring monthly subscription [11]. 🛠️ How to Find or Redeem Your Code Adobe Photoshop License Key
Activation servers for very old versions (CS2, CS3, CS4) have been retired. These versions can no longer be activated through standard online methods [23]. No serial number is required
Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Photoshop [2]. Adobe Photoshop License Key
Look for a key named or LicenseKey (note: this may be encrypted) [2]. ⚠️ Important Considerations
If the software is currently installed, you may find the serial number in the Registry: Open (Registry Editor) [2].