It is possible to lose your residence permit for certain reasons. This is called revocation. It means that UDI decides that your residence permit is not longer valid. It can entail either that you will no longer be allowed to live in Norway or that you will be granted a new residence permit and your period of staying in Norway restarts.
There are different reasons for potentially losing your residence permit, including:
For more information, see Revocation - when a residence permit or citizenship is invalidated.
If you are going to change host families, you must apply to renew your residence permit. If you do not apply for renewal, you risk losing your residence permit.