The safest way is to buy directly from ABBYY or authorized resellers.
To convert the software from trial to full mode, a valid serial number (the license key) is required. Standard Activation: Open the software and navigate to Help > Activate Enter the serial number provided at purchase. Select the "Via the Internet" method for immediate automated activation. Offline/Manual Activation: If no internet is available, select "On the web-site" in the Activation Wizard to generate a Product ID ABBYY Activation Page abbyy finereader 15 license key
For secure environments without internet: The safest way is to buy directly from