The main goal of Excel file copy protection is to remove formulas from cells to make them unavailable to anyone. If the formulas are not really secured protected  then anyone who get permission to launch your model, (even if it was protected with password, license key and/or with hardware locking),  may copy all data and formulas (manually or using some Excel Add-In) into another unprotected workbook and use your model without any restrictions.

The DoneEx XCell Compiler compiles all formulas from xls into binary format and remove them from the cells of xls.

In order to reach this goal, the calculation engine was created to substitute the original Excel's calculation in compiled EXE whereas the Excel itself is used for formatting and reflection of calculation results.

This is the only way for real workbook algorithm protection. 

Even encoding with strong encryption algorithm is not so secure because you should provide decrypt key for user and since this moment your data are decrypted and available for anybody.

• To check if there are any available formulas in any compiled EXE  you can switch Excel in "Formula Auditing Mode".
  

• To check that formulas are not available from VBA code  you can use the following equation in VBA

The secured formulas protection is available for any type of DoneEx XCell Compiler licenses . To protect your formulas you just need  to compile your xls with DoneEx XCell Compiler. Please see how to compile your model.