You must purchase a key to unlock (register) your software.  After the transaction is completed, you will receive an unlock code by email.  It will arrive in whatever email you use to complete the purchase (through PayPal or Google Checkout).  Sometimes these keys get caught by junk mail/spam filters, so watch out for a message from This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Instructions will be included with the unlock code that explain how to use it.  Once you've unlocked the trial version, it will become the full version.