The Adobe LiveCycle Reader Extensions is software that users can use to enable some features, in Acrobat Reader (now Adobe Reader) 5.1 and later on a per-file basis. These are features otherwise found in the full licensed product Adobe Acrobat.
For example, Adobe Reader cannot normally save filled in forms or apply digital signatures. If LiveCycle Reader Extensions is purchased with suitable options, it can prepare files that Reader can save or sign.
LiveCycle Reader Extensions is sold on a quotation basis, and the price will vary according to the number of forms and end users, on the basis that these are nominally lost sales of Acrobat. The original marketing target was large businesses and government organizations such as the US Internal Revenue Service (who make savable forms available through this technology).
Smaller businesses have wished there was a service for enabling single forms at lower cost. Two Adobe partners have contracted to provide this service for companies at a fee per page and use, user or form.