I did not "make it up on the spot", I simply read their website:

"Typically incidents are chargeable when they require work from us such as writing, compiling or testing patches, updating documentation, analysing or debugging your code, finding workarounds, providing technical advice or other significant effort.

In particular, please note that we may regard fixes for bugs in its own Lisp products, and for shortcomings in the documentation, as chargeable."

Source: http://www.lispworks.com/support/description.html#chargeable

Note how the list and following text clearly indicate that you can and will be charged for bugs in their own products.