Will I Remember the Milk?

I recently received some vaccination and the vaccine regimen requires re-vaccination in three years' time. I don't want to miss it but how do I schedule a task that is three years out?

I keep my to-do list on Remember The Milk and I am a huge fan of the service. I can access it from my Mac and phone, I get reminders via Skype and my to-do list is integrated with Google Calendar. On the other hand I am fully aware of the limitations of Chatswood, Australia based Remember The Milk Pty Ltd. The company can go out of business or I will switch to better to-do list management service (which is different from calendaring service).

RTM is great for my next week's or next month's tasks but will I trust it with my next vaccination? Given that RTM exists for last three years and they have a great track record so far I think I will take the risk. But will I remember it in three years?