Yes! You are under no obligation or contract to stay with Pro-Stitcher under the monthly membership plan. You can cancel at anytime by going to Account > Membership and selecting Cancel. Anything you’ve purchased will remain associated with your account/email address, and you can rejoin at any time.
By selecting Cancel, you are saying “do not renew my purchase when the next billing opportunity happens.” If you cancel an annual membership, it will simply not renew the following year.