Multi-user licences give buyers a number of licences and often come at a discounted price. Most software education licences can be purchased in multi-user form and as a general rule the more licences you purchase the greater the discount. Many system administrators prefer such volume or 'site' licencing as it often makes managing installations and storing licence details easier.
As a general rule, if you need 5 licences or more you should ask if a multi-user licence is available for that product.
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