I've just bought a license. What do I do?
Copy and paste your license key into PageFour's License dialog. The License Dialog can be found by opening the Help menu within PageFour. This is what the help menu looks like. If your trial period has expired, the License Dialog will appear automatically when you open PageFour.
Apologies in advance for this next statement, but if you cannot find the help menu, you need to download and install PageFour. PageFour is desktop software, not a web application. If you have purchased a license without trying out the software, you should go to the download page, download and install the software, and run it. You will then see the Help menu, from where you can open the License Dialog and copy in your license key.