The pro forums are accessible to those with an active pro subscription. This provides a way to offer pro support, helps stop unauthorized redistribution, prevents lite users from trying to add changes only meant for the pro version, and besides, what you would be purchasing (if you purchase) is a pro license, not anything from the hacks and modifications forum nor code posted in the other pro forums. If you have a question about whether a particular pro feature or modification exists, that is a good question for the pre-sales forum
here.