Do I need to cancel my Google Play subscription separately before deleting MY.PROTECTSTAR?

Yes — absolutely. If you have an active subscription through Google Play, you must cancel it separately directly in Google Play. Deleting your MY.PROTECTSTAR account does not automatically end that subscription. Protectstar explicitly notes in its account-deletion FAQ that Google Play subscriptions must be managed or canceled separately. Google also confirms that uninstalling the app alone is not enough: without a cancellation, billing can continue.

How to cancel the subscription correctly:

1. Open Google Play on your Android device.
2. Go to Subscriptions.
3. Select the subscription in question.
4. Tap Cancel subscription.
5. Follow the remaining instructions.
   Google also explains that when you cancel, you usually keep access until the end of the current billing period. In other words, cancellation normally stops the next renewal, not the period that is already running. 

If you cannot find your subscription:
Then it is often linked to a different Google account. Google explicitly notes in its subscription help that some subscriptions may be under another account and that you may need to switch between accounts. Important: “subscription not visible” does not automatically mean “no subscription exists.”

The clean order of steps is therefore:
First cancel the Google Play subscription, then — if you want — delete the MY.PROTECTSTAR account.

You can also find more information here https://www.protectstar.com/de/faq/how-can-i-delete-my-myprotectstar-account