After five years of ownership how is the fee collected?

Fees can be paid in a single yearly payment or in monthly instalments.
The Post Sales Help to Buy Agent will collect your fee by direct debit or standing order. They will contact you at least one month before your fees are due, to set up your repayment arrangement. If you do not pay by Direct Debit, you will pay an additional administration charge which is currently £4 per month.
You will also receive a statement each year confirming when your fees are payable. The annual statement will also show any payments you have made once you start paying the fee.