HEPA, or high-efficiency particulate air filters, filter out particles as small as 0.3 microns and keep them from being released back into the air by your Maya V2's exhaust.
It's recommended that you replace the Maya V2's HEPA filter every six months (twice a year), but it depends on your vacuuming habits. If you use Maya V2 on a daily basis, we recommend you to do that every two to three months.
If you notice a reduction in your Maya V2's suction power before then, you should consider replacing the HEPA filter. Be sure to clean the filter at least once per week or twice per week if you have pets.
See how to replace the HEPA filter of your Maya V2 here.