In Germany when Rohloff boxes were first fitted to touring bikes, the idea was that the bike would be returned once a year to a factory-trained mechanic at the dealer who supplied it for its annual service. It wasn't indicated who would take the EXT box off (one thumbscrew) every 500km, clean it out and fit it back up (one thumbscrew while jiggling the rotary gear control). Such a hardship! You can find elsewhere on this forum my logic for and experiment in greasing the EXT box every time the oil is changed (or, theoretically in my case, when the bike has been beyond hub-deep in water).
Since I live in Ireland where there are no dealers for the German baukasten, I made an arrangement with the maker of my bike that the local blacksmith who calls himself a bike mechanic would do the job and, this being the most important part, sign the tangerine record. Since the LBS had a talent for breaking things that were expensive to source from Germany, the arrangement worked out that I would do the work, and take the piece of paper along for him to sign, something I soon got bored with. That was about twelve years ago, and I haven't had a warranty claim but the box and the frame is now out of the ten year warranty the manufacturer of the bike gives on top of Herr Rolloff's warranty. I can't say I've been overly worried that anyone won't do the right thing in all this time.
If the box you bought new, it is worth filling in the service document and keeping a record of the dates and mileages of services, as Tiberious outlines above, because Herr Rohloff gives, within his goodwill, what is essentially a free extended warranty to first owners of his gearboxes who haven't abused them, though recently there have been some rumblings about some people abusing his goodwill.
