I still think a user manual could help
Not likely to happen. The professional plugins have rapid development, which means they change too frequently for anyone to keep up with in regards to writing documentation.
How is one supposed to know that putting 2 conditions won't work ?
Trial and error. Subscriptions are tiered based off experience. We expect professional subscribers to not be new to Joomla, CB, or web development in general. 2 conditions can work, but it needs to be setup right.