In this case contact our support and specify the following information:
- What kind of error occurred during the activation process
- Link to the site where you bought the product
- Your account ID on the site (it is specified in your account in the "Settings" section) or email you used to make an order
- What product did you buy
- Screenshot with information what you enter in the Steam client, and also how you do it
- Screenshot with error notifications after key entry
- Screenshot of your Steam library
We will definitely help you to find a solution to the problem with product activation!