When activating or updating an eBay account via OAuth2, a token is generated that is valid for 18 months.

Important notes on validity

• No warning: You will receive no automatic warning when the token expires.
• Change of credentials: The token also immediately becomes invalid if you change your credentials (e.g. password) directly on eBay.

In both cases, you must update the account in the menu Setup » Markets » eBay » Accounts » OAuth2.