Types of licence
You (usually) have a number of choices as to how you purchase each licence (commercial software), either as a one off or part of a bigger contract.

The choice available to you in terms of the types of licences can be extensive.

In reality there are very few that you need to be concerned with.
 
So rather than purchasing the first thing that looks right, make sure you understand the basics of licence types and especially volume agreements as a great reduction in costs can be achieved by procuring licensing in the right way.

What are they?

Starting from the least expensive:
Freeware - You don't have to pay anything as long as you adhere to the details in the licence, for example it might be free for personal use or non-commercial use but require a licence in the corporate environment - see the front page of this section for explanation of GNU General Public Licence.

Shareware - Distributed without payment on a trial basis or limited period.

Evaluation - Same as shareware, i.e. you can download and install the software for a certain period after which you have to purchase a full licence to continue using the product.

Commercial licensing:

There are two types of 'one off' commercial licences that can be purchased:
OEM - The software licence is tied to the hardware with which it is purchased.  It is also the most likely form of counterfeit licence - OEM

Retail or boxed product - This is the most expensive form of licensing and widely available in counterfeit form - Boxed product

Contract licensing - It is then possible to purchase licences under contracts such as volume agreements.  This is by far the cheapest and safest way to purchase software licensing.

You often have a choice between a full licence and an upgrade licence in both retail and volume agreement formats.

Subscription licensing
- If you do not wish to purchase your licences outright, you can enter contracts where you pay an annual fee to have the right to use that software.

Finally in this section we look at Licence transfers...