Rights granted by copyright regarding software
Almost anything that can be done with a computer program is covered by the copyright of the author. Of particular interest in the case of software is distribution (copying) and the creation of derivative works. To be allowed to obtain and use a program, permission must be obtained from its copyright holder. This is called a license.
Copyright generally makes no distinction between commercial and noncommercial activities, or between large-scale and small-scale distribution. Sending out a single copy for evaluation purposes to an external customer is under copyright law the same thing as selling a million copies. Without permission from the author, both are forbidden.
Of course the damages to be paid by the infringer will be higher for large-scale commercial distribution than for a single non-commercial copy.
Using software almost always involves creating copies, even though many of these copies only exist for a very short time. For example, executing a program means copying it from the hard disk into RAM so that the CPU can interpret the instructions. Because of this, the right to run a program is considered to fall under the copyright of the author. Most copyright laws state that despite this fact, lawful acquirers of software are allowed to run the program.
The license under which the software is made available may impose restrictions on where and how the acquirer (licensee) may run the program. For instance, the license can be specific to one computer system or be time-limited.
Distributing copies of software, whether on a carrier or via a network, is covered by copyright. This is only allowed if the copyright holder has granted permission for the distribution.
The same of course applies to downloading and installing the software. These activities also involve the making of a copy. If the software is offered for download by the copyright holder or an authorized distributor, there is a so-called implied permission to download and install. The only reason for offering the software is to allow people to download and install.