In general, we do not charge for support if you are running a current version of the software.
We have over 1,500 installations and we really don't get many calls so that's why we don't charge. Now, if you are running a really old version of the software then we sometimes have to charge a dollar a minute for a really complicated question. But that rarely happens.
We like it when our customers call us because then we find out what sort of enhancements will make the product "better" - and then we incorporate these ideas into the next released version - which makes the software better for everyone.