In general, licenses usually do NOT allow the software to be installed or resident on more than a single machine, or to run the software simultaneously on two or more machines. Historically, the Copyright Law was modified to permit certain educational uses of copyrighted materials without the usual copyright restrictions. For most software it is clearly illegal to make and distribute unauthorized, fully-functional copies to class members for their individual use. Making copies of a small section of code from a program in order to illustrate a programming technique might not be a violation. The best alternative is to clear any such use with the copyright owner or consult the appropriate authorities at your institution.
Software can be expensive.
You may think that you cannot afford to purchase certain programs that you need. Site-licensed and bulk purchased software are legal alternatives that make multiple copies of software more affordable. Many educational institutions negotiate special prices for software used and purchased by faculty, staff and students. Consult your campus computing office for information. As with other software, site-licensed or bulk purchased software is still covered by copyright, although the price per copy may be significantly lower than the normal commercial price.