You can, but there's nothing that states that you have to go through Nissan for your service.

All you have to do is maintain records of the service done along with the mileage on the car and VIN. (Obviously it's your car, so keeping track of the VIN is easy)

I do all of my work myself or with my brother's help and I keep track of it with my iPhone. I use an app called GasCubby. It's about $6 and it's tailored for keeping track of mileage and MPG, but it can be used for any kind of maintenance. You can set up alerts to remind you at custom intervals for oil changes, etc. The database can also be exported to Excel and it supports multiple vehicles.