No, there is no need to create a separate screensaver for each customer. The seed in combination with the customer name serves as a starting point to create unique license keys for your customers.
When creating a screensaver:
1) Choose a seed. It might be a zero, but I suggest choosing something else and more difficult to guess.
2) Set up registration data by selecting “Unique registration keys” and entering the chosen seed in Selling > Registration > Key seed.
3) Make the screensaver and upload it on your webpage.
When you need to generate a key, run the Registration Key Generator, enter your seed and customer name. The Key Generator will return a unique license key. The idea is to use the same seed in both the screensaver and Key Generator to get valid licenses for the customer.
Run the Key Generator by pressing Key Generator button in Selling > Registration. Or run keygen.exe directly from c:\Program Files\Screensaver Factory (or Program Files (x86) on 64-bit Windows).