computer software which is offered free to customers for a period of time, after which the supplier sends frequent messages to the customer, asking them to buy the program
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nagware UK US /ˈnæɡweər/ noun [U] IT, MARKETING
► software that tries to make users buy a program, service, etc. by making pop-ups (= small screens that you need to click on to close) appear regularly on their computer screens
Financial and business terms. 2012.