When you integrate LinkedIn and Demandbase an access token is generated for Demandbase to access your LinkedIn ad account on behalf of you. This is how we are able to create, manage, and update your audiences.
When a LinkedIn access token is generated, it is good for 1 year. After 1 year has passed, if you do not reauthenticate your LinkedIn integration, your access token will expire and your integration will not work.
You can reauthenticate at any time to prevent this from happening. See Manage Ad Accounts.
You are notified in advance as your access token approaches its expiration date. We will send you notifications 1 month, 3 weeks, 2 weeks, and 1 day before your access token expires. If you still do not reauthenticate, you will get a notification every day until you reauthenticate to generate a new access token.
If you allow your access token to expire, you will notice a red past date next to the LinkedIn data source in 
Settings > Demandbase-Wide Settings > Integrations.
Demandbase One