We truly appreciate your support! However, we really don't want someone to pay for AdBlock if it represents a hardship. We'll be happy to issue a refund. Just send the Order ID from our thank-you email to firstname.lastname@example.org and we'll get that taken care of for you!
If you're seeing our payment page more than once after installing AdBlock, it means that AdBlock's settings are being reset to the defaults. Basically, AdBlock thinks it's just been installed. Here are a couple of Knowledge Base articles that should help: