Site / Enterprise license

Unlimited use throughout an organisation; forgoes per-install registration.

Single-user license

Installable on one personal computer (plus often one extra owned by the licensee).

Multi-user / Groupware

Licensed by number of computers/nodes, or purchased by number of users.

Shareware

Trial or demo software, limited by functionality, availability or convenience.

Freeware

Offered at no cost; may or may not be copyrighted or reusable in your own code.

Free / open source software

Freely used, modified and redistributed, provided the same free terms carry forward (copyleft).

IP, Copyright & Software Licensing