To trek in Nepal, you’ll need to go through a travel agency with a trekking license. For trekking in general, the travel agency will have to fill in a Tims card (Trekking Informations Management System) with the information of the trekker, you. These cards are subject to a fee, and certain permits are also required, depending on the trekking zone chosen. The travel agency will need to fill in the Acap (Annapurna Conservation Area Project) if you’ll be trekking in this area, for example, or Mcap for the Manaslu Conservation Area Project.
To use these permits, simply send a copy of your passport to the travel agency, so that it can fill in all the necessary information.