Confirm you received it
Reply quickly with the end date and what that means for billing.
Check the notice terms
Look at the notice period and renewal date in the contract.
Ask why, once
Invite the reason in one short question, without pressure.
Offer a real fix
If the reason is fixable, offer a specific change or a call.
Explain the wind-down
Say how to export data and when access ends.
Leave a good last impression
Thank them and say they are welcome back.