Software and other media are going to a subscription model more and more. No matter what you think of subscriptions, I do not think they are going away any time soon. If the software you are subscribing to is in the App Store, then the subscription is managed through the iTunes App. To cancel or at least check on a subscription you must login to your account on the iTunes Store. Here is how that is done.
To check on or cancel a software subscription you login to your account in the iTunes App:
You will be taken to a screen with a bunch of your information on it. You have to scroll down the page to the bottom to access your subscriptions:
When scroll down to the bottom of the page you will see your Subscriptions link:
Just click on Manage and you will see a list of your Subscriptions in the iTunes Store:
If you click on the App there is usually a Cancel link or button in there somewhere:
After you Cancel, just click on the Done button and you really are done.
Checking on Apps or Services subscriptions is easy in macOS. All you have to do is go into your Account in the iTunes Store.