Yes, if trekking outside of Nepal, but there’s no cover if trekking on unrecognised routes.
If you are trekking within Nepal you must have our Nepal Trekking Activity Pack add-on included and there is no cover for trekking without a guide.
We do recommend going with a qualified guide or group of no less than 3 people, as search costs and non-medical rescue costs aren’t covered, only rescue from a known and agreed location is. The search aspect is usually cut out completely, or minimised, when trekking with a guide as they may carry some sort of GPS tracking with them and have an in-depth knowledge of the area. Whereas if you’re injured without a guide you may have a hard time describing your location to the helicopter rescue services, if you can contact them at all.
Altogether it’s a lot safer going with a guide, which is why we recommend it, but going without one doesn’t invalidate cover (outside of Nepal) provided you use recognised routes and take all necessary precautions.