Air filters for your home can be purchased and used 30-90 days. I like the 90 day filters because I do not have to charge them too often.
In your home locate the vent which may look different than the image above.
Open the vent by flipping open the two small latches located at the too.
Remove the old filter from the vent.
Most filters will have an area to use for making a note of the installation date. If not, be sure to write on it somewhere.
I use a sharpie marker but a pen can also be used too.
I write the month and date on the filter and also record a reminder on my iPhone or home calendar.
Install the filter with the arrow pointing in the direction of the air flow from your vent.
Close the vent door and enjoy the rest of your day.