BlackBerry Ltd. on Friday announced new privacy measures for its BBM messaging service that will eventually be offered, along with other services, for a fee. One such feature allows users to set a time when their sent messages will expire, BlackBerry said in a press release. The feature does not prevent a screenshot from being taken of the message but users will be alerted if that happens, BlackBerry said. When this feature is used the recipient has to keep touching the screen in order for the message to be visible, the company said. The company also said users will have the option of retracting messages they send through BBM. BlackBerry said these features will be available for free for three months, after which they will become part of "broader bundle of features that will be offered as part of a BBM subscription." No details on pricing or other features that will be included in this subscription package were provided. As BlackBerry tries to diversify its business beyond selling smartphones, it has cited monetization of its BBM service as a priority.