Subscription changes

Happy Wednesday! My promo “ trail “ will be up soon and wanted to switch from monthly to an annual subscription. I sign on thru Apple AppStore ( with some confusion about email address ) for a three month reduced cost. How should i go about the change when the time comes? Should i cancel prior so monthly auto payement stops and then re-subscribe to a yearly?
Cheers!
Milo and younger brother Escher

Answers