Hello Matt
According to our terms and conditions
www.joomdonation.com/terms-and-conditions.html
, we provide free upgrade and support for one year for each purchase
After one year, the products will still work well on your site, so you don't really have to upgrade unless you want to update to use new features provided by the extension
In ideal world, you won't have to update during Joomla 3.x releases. Unfortunately, there are some backward incompatible changes in Joomla core API in version 3.6.0 and 3.7.0, so upgrade are required for some extensions
I checked your account and only found Events Booking order. So you can submit a support ticket sending us PayPal Transaction ID of your Payment Form and Joom Donation purchase. We will find these orders and if it is valid, we will offer you some discounts for upgrading. Please submit a support ticket so that we can discuss more details about it
Regards,
Tuan