Hi,
Unfortunately, I don’t think our plugin can cancel membership at the moment. I could try to implement it, but to be honest, I’m not sure which “WooCommerce Memberships” plugin function should I call to cancel membership for a user. Will be looking into it more…
P.S. I’m not sure if this will help, but some of our plugin’s users were using the membership subscription start date as a date to start counting products from. I.e. instead of checking the last 30 days, the plugin will check how many products did user buy since his membership subscription start date. If that’s something that may help you, let me know, and I’ll help you with setting this up on your site.