Ios app says problem purchasing the subscription but my subscription is active?

Let's verify the status of your subscription, bettermethanyouh.

It's possible that your account is expiring and one of your users attempted to re-subscribe the account. Here's how:

1. Login your account on a web browser.
2. From the Gear icon, select Account and settings.
3. Go to the Billing & Subscription tab.

Afterward, you're good to login to your QuickBooks Online app. 

Also, if you want to update your payment information, you can check this reference: Manage billing, payment, and subscription info in QuickBooks Online.

I'll be around if there's anything that I can help. Keep safe!