A computer-implemented method comprising, at a client device: displaying to a user of the client device an interface including a plurality of pages (512a to 512g) of a digital content, the plurality of pages of the digital content being a sample version of the digital content; identifying a point of interest included in a page of the plurality of pages of the digital content, wherein the point of interest is a purchase point defining a point in the digital content up to which the digital content may be displayed on the client device before a full version of the digital content is purchased and installed on the client device; assigning a physics model to the identified purchase point, wherein the physics model defines how the pages of the digital content move through a view frame of the interface when an interaction with the interface for moving the pages forward or backward through the view frame is received from the user, and the physics model assigned to the purchase point results in the page which includes the purchase point coming to rest within the view frame, when the page including the purchase point enters the view frame, and in the digital content being purchased and installed upon performance of a user interaction via the interface to move past the page including the purchase point subsequent to the page which includes the purchase point coming to rest within the view frame; receiving from the user an interaction with the interface for moving the pages forward or backward through the view frame; responsive to receiving the interaction from the user, moving the pages through the view frame and applying the physics model such that, when the page including the purchase point enters the view frame, the page which includes the purchase point comes to rest within the view frame; receiving from the user a subsequent interaction with the interface to move past the page including the purchase point; and in response to receiving the subsequent interaction from the user, instructing purchase of a full version of the digital content for the user, and after the purchase, causing the full version of the digital content to be installed on the client device. displaying to a user of the client device an interface including a plurality of pages (512a to 512g) of a digital content, the plurality of pages of the digital content being a sample version of the digital content; identifying a point of interest included in a page of the plurality of pages of the digital content, wherein the point of interest is a purchase point defining a point in the digital content up to which the digital content may be displayed on the client device before a full version of the digital content is purchased and installed on the client device; assigning a physics model to the identified purchase point, wherein the physics model defines how the pages of the digital content move through a view frame of the interface when an interaction with the interface for moving the pages forward or backward through the view frame is received from the user, and the physics model assigned to the purchase point results in the page which includes the purchase point coming to rest within the view frame, when the page including the purchase point enters the view frame, and in the digital content being purchased and installed upon performance of a user interaction via the interface to move past the page including the purchase point subsequent to the page which includes the purchase point coming to rest within the view frame; receiving from the user an interaction with the interface for moving the pages forward or backward through the view frame; responsive to receiving the interaction from the user, moving the pages through the view frame and applying the physics model such that, when the page including the purchase point enters the view frame, the page which includes the purchase point comes to rest within the view frame; receiving from the user a subsequent interaction with the interface to move past the page including the purchase point; and in response to receiving the subsequent interaction from the user, instructing purchase of a full version of the digital content for the user, and after the purchase, causing the full version of the digital content to be installed on the client device.