Applying for a permit online is a three stage process, firstly you need to register with RingGo, then complete the permit application form and once that has been approved you can purchase your permit.
Permits are available for three months or a year. Permit applications need to be renewed annually so if you purchase a three month permit you do not need to renew until a year has passed. To buy another three month permit against your annual application, log in and then go to the permit application page and click on the money icon against your application.