Fair enough... but how about allowing people who have already bought more than $99 of software from you to activate without the fee? Even if they do it a month here and a month there, they have proved they're serious, they're clients, and you'd get their money again. (Yeah, I'm thinking of myself!) Also, downloading new versions and activating is a chore, so someone would have to have too much time on their hands to it every few months just to save $20/$40.
There's got to be a way to check for valid subscription and then, if that fails because the subscription is expired, to read an encoded value in the Webassist files that matches the code with the product (to make sure I'm not using a newer, unpaid-for-version). If the old, expired product's validation matches the older Webassist module file, then I am allowed to use the expired product for maintenance.
All this for the future, I hope!