Hi guys, I think my annual subscription is about to expire but I can’t find out the date or how to pay for another year? Anyone know where I can go use my credit card? 
Go into the app, Settings, Billing, Manage your plan…
At least in iOS, you’re instructed to log into SYSTM on the web to deal with billing. Log in here:
https://systm.wahoofitness.com/home
Then follow instructions above.
IDK about iOS but in Windows I can manage my subscription form the downloaded app. I can go to the website app and it looks and works just like the downloaded app (incl billing) , but I can’t do workouts from it. It says I need to download the app to do a workout.
I think the peculiarity in iOS is Apple’s “commission” on in-app purchases. To avoid those, you can’t allow direct subscription management from the app.
You can also subscribe to SYSTM through Apple. If that’s the type of subscription you have, you manage it through Apple, not Wahoo. (Click Settings then your name at the top then Subscriptions). It should auto-renew unless you cancel ahead of time. I think Apple only offers monthly subscriptions and it obviously costs more for Wahoo.