Most license keys are generated immediately after purchase. Check the you used during checkout. Look for a message from the vendor with a subject line like "Your Order Details" or "License Key Information."

In your dashboard, click the button next to your product.

If you're stuck, most reputable companies provide a Knowledge Base or documentation page that gives step-by-step screenshots for their specific interface. [Cerrado] Where do i add license key? - Toolset

Before you can use the key, you need the software installed.