When you purchase a copy of Microsoft Office 2010, you're provided with a unique product key that serves as a license to use the software. The product key is a 25-character code that's used to activate the software and verify that you've purchased a legitimate copy. Without a valid product key, you'll only have limited access to the software's features, and you'll see reminders to activate the product.
If your product key is not being accepted, check for these frequent pitfalls: enter your product key microsoft office 2010