Secret Word is using by Mighty Membership payment plugin "Pay Bill" to strict some subscription plans to be paid by bills and allow other subscription plans. Secret word works this way:

- set secret word in Invoice configuration;

- install and publish Pay Bill Membership payment plugin;

- edit subscription plan which you want to allow paid by bill. Just insert the same secret word to plugin Pay bill under subscription plan settings - see tab "Payment Bill" parameter Secret Word.

After this users may use pay bill to purchase subscription plans which has the same Secret Word in "Payment Bill" plugin parameter as Secret Word is set in Invoice configuration.

If you want to sell from Content component it is very possible. For example you are a hosting company and every content item is a hosting plan. And you want to have a Buy Now button for every plan. Or you are a tour operator and every content article is a tour description and you want to have an Order Now button there.

For that you need to create a URL type field. Then, when you create an article insert bill URL into it.

Note that you can append amount and description parameters to the URL. For example if you want one bill title but different amount.

Yes, that is easy. We have technical article here on how to integrate Bill with other components on plugin base.

Bill is very flexible and it has one feature that allows you to let customers purchase the same bill endless (or limited) amount of times. This type of bill is more like "Product". As a bill number you need to enter product SKU which will be always the same for every transaction. More than that, in report center you can get a diagram on this product (bill) sale process.