When you next log in, follow the instructions to upgrade. Don’t worry, you won’t need to enter any payment details. This will direct you through the sign up process and start your 14 day free trial. At the end of your free trial, you have the option to subscribe to Analyser and will be prompted to add your payment details to do this.
If you choose not to sign up at the end of the trial, you’ll simply not be able to access Analyser any longer.