You need to file a one-time Section 8 Affidavit:
after the five-year mark and before the sixth anniversary, after the issuance of the registration
another Section 8 Affidavit in ten years from the initial registration date
after that, you will have to file a Section 8 Affidavit all subsequent ten-year periods while you still want the trademark registered.
You can file the affidavit at any time after the nine-year mark of each ten-year increment.
The affidavit must be accompanied by an example of the trademark and a filing fee of $100 per class. If you need an extension, you can request a 6-month grace period over the six-year and ten-year deadlines, but you need to pay an additional cost of $100 per class.
If you fail to file the Section 8 Affidavit the federal registration of your trademark will be cancelled.