How many machines is it OK to have it installed on ?
Reason I ask...If I was to use the unclogger part of the program, in order to print at regular intervals it would need to be installed on a machine that is always on.
My server is always on, but my main machine where I would mainly use QI isn't always on.
Does the license of a single purchase allow it to be installed and running on two machines ?

You may install it on multiple machines as long as only one copy/person is using it at one time.
So running the UNCLOGGER on one, and using QU on another is a great idea.
Fred

"Unless otherwise specified in your registration email, you are granted a
single license for Qimage. This license authorizes the use of one
copy of Qimage to be run at any given time. A single user can
install Qimage on multiple computers if only one copy of Qimage
will be running at any given time. In addition, Qimage can be
installed on a single workstation and used by several users if only one
copy is in use (one person is using the software) at any given time. If
you require more than a single license under these conditions,
additional copies must be purchased. Discounts are available for 10
copies or more. Inquiries regarding multiple copies or site licenses
are welcome and should be addressed to mchaney@ddisoftware.com."

The "spirit" of a single user license is to ensure that only one person is using the software at a given time.  So to expand on the wording in the EULA, you would only be using one copy in that situation.  The one running the unclogger is, for lack of a better phrase, "using itself".    So you're fine.

Mike