You do not have to switch. If you would like to move to website billing, cancel your store subscription first so you are not billed twice.
Cancel your subscription in the App Store or Google Play. You keep access until the end of the period you paid for.
Sign in at app.hilo.com and open the Membership tab.
Select Manage my subscription and complete the website checkout. Use the same email address as your Hilo account.
The web portal cannot cancel a store subscription for you. It will point you to the App Store or Google Play.