I want to cancel my subscription
Genius Scan+ is a one-time purchase. If you purchased Genius Scan+, it's a one time purchase and you won't be charged on a recurring basis.
Genius Scan offers one subscription, called Genius Cloud, which offers document backup and storage.
How can I check/cancel my Genius Cloud subscription?
You can check that you have a subscription (or cancel it) on Manage My Subscriptions.
You can check that you have a subscription (or cancel it) as explained by Google here.