If there are existing subscription products and Enable Subscriptions is subsequently turned off in settings, you can disable the setting while the product still remains a subscription product, but the subscription options are removed from the product edit view. Then if the user wants to disable subscriptions for that product, they are unable to do so without knowing they need go into settings and re-enable subscriptions to see the settings and make the changes.
Possible solutions:
When disabling subscriptions check to see if there are any active subscription products and don't allow disabling unless there are no subscription products.
—or—
When displaying products details, check to see if the product is a subscription-type product. If it is, always display the subscription settings, regardless of whether or not subscriptions is enabled.
For the second solution, check the Enable Subscriptions feature and see if there is any reason to not do this. I think I lean toward the first solution.
If there are existing subscription products and Enable Subscriptions is subsequently turned off in settings, you can disable the setting while the product still remains a subscription product, but the subscription options are removed from the product edit view. Then if the user wants to disable subscriptions for that product, they are unable to do so without knowing they need go into settings and re-enable subscriptions to see the settings and make the changes.
Possible solutions:
For the second solution, check the Enable Subscriptions feature and see if there is any reason to not do this. I think I lean toward the first solution.