Renewals on patents become payable on the 4th Anniversary of when the patent was filed and then every year after that (near the anniversary due date) for up to 20 years. Renewal fees are paid for the year in advance, so you are paying the 5th year renewal fee on the 4th anniversary of the patent.
If you decide to take on the responsibility of renewing, then you bear all the responsibility for making the payment on time and for the correct amount. The risk is that if no strong system is in place to track deadlines, and a deadline is missed, it is costly and it is not always possible to apply to restore your rights.
With the supported Patent Place platform, this risk is alleviated as it is designed to track and flag all relevant renewals deadlines giving you peace of mind that your renewals are in safe hands.