You ony need to pay the inital purchase cost to buy a lifetime license. The annual subscription covers "updates and support" so isnt mandatory for the plugin to continue to function. Frustratingly they dont tell you how to cancel the subscription (you have to raise a support ticket). This is the information they sent me when I asked how to cancel..
A recurring payment is created when you check out through paypal.
To cancel the recuring payment:
1. log in to paypal and select profile from the top right
2. select my money
3. select my pre-approved payments
4. select the payment for weDevs LLC
5. cancel the pre-approved payment