Why no bites is not the answer
Not everyone reacts to bites, and reactions can take days to appear. Bed bugs can also survive several weeks without feeding, so a quiet week after treatment may simply mean they have not fed yet.
Eggs are the other problem. Most treatments do not kill every egg, and the survivors hatch over the following two to three weeks. That is when a room that looked clear starts again.
What actually settles it
A count. A monitor placed at the bed legs draws bed bugs with the scent they use to find each other, and counts each one that walks in. Zero over the weeks after treatment means nothing is moving. A count means the treatment needs a second pass.
The important part is that it keeps counting while you are asleep, and it does not need you to lift it and look. You open the app and read the number.
How long to keep watching
Leave the monitor in place for at least six weeks after the last treatment, which covers the hatching window and a full feeding cycle. Most people simply leave it there, because the lure lasts a year and the box is not in the way.