Should you use VBA for building Excel custom UDF's when performance matters? Are C# and VB.NET faster or slower than C++?
How to get the latest Excel formula functions like TEXTJOIN, CONCAT, MAXIFS, MINIFS, IFS and SWITCH to work on Excel 2007, 2010 and 2013?
Excel is very powerful, but using it in a wrong way can make your life more difficult. Just make sure not to make some of these mistakes.
If you're in the business of selling Office apps, you want to prevent others from stealing your code. Here's my recommendation.