Original Equipment Manufacturers (OEM) products are configured to print only the amount of ink held within the product. Within the compatible industry, it is quite common that a compatible cartridge holds more ink than that of the OEM. Therefore, once the printer has printed its recognised quota of pages, the printer will automatically prompt you to change the cartridge. Usually, a simple press of the resume button will temporarily override the ink monitoring. Printing will continue but further regular warnings will continue to appear if the cartridge isn't replaced.
However, it is not sensible to run a cartridge dry in this way as it can cause a number of issues.
Firstly, when a cartridge is completely empty and further printing is attempted, air is pushed into the printhead instead of ink. This can cause problems when a replacement cartridge is installed. If after cartridge replacement the printer suffers poor print quality or even no ink at all coming through (after making sure first that the plastic tear off PULL strip has been fully removed), it is probably not the cartridge at fault but more likely to be an airlock between the cartridge and print head. Usually a head clean will help push any excess air through the system, after which printing can resume successfully.
The second reason for not running a cartridge dry is to reduce the risk of overheating the print head. Ink also acts as a lubricating coolant when running through the printhead, and without it, the printhead stands more chance of becoming burnt out and permanently damaged.
Lastly, having an empty cartridge installed in your printer increases the risk of blocked heads. When the printer is left for long periods of time without being used or with an empty cartridge installed, ink residue on the head can dry out. This forms clots of ink on the head, which in turn, can clog the system and lead to poor performance.