If you are serious planning to become an expat in Nepal the best way is to participate as a shareholder to an existing expat company. Shareholders are able to get a multiple entry business visa for long term stay ( first one year and after renewal it will be every time 5 years).
The only other way to stay long term is to marry a Nepalese and that is far more complicated.
If you have enough money you can also start your own company in Nepal. At the moment investment required is a one time sum of US$ or EURO 100,000 that you have to bring into your bank account in Nepal and you can start by registering at the Department of Industry.
We recommend the Nepal Standard Chartered Bank (LTD) for sound business because it is the most powerful and reliable bank up to date in Nepal. Anyone can open a private Bank account in US Dollar or EURO here (Euro may be better now)...even a regular visiting foreign tourist can remain a foreign currency account in Nepal. However..the money that you have parking there is only paid to you in Nepalese Rupees (day rate) when you withdraw some. But of course you have the right to shift it back to any bank abroad if you think that Nepal is not safe anymore.
Next is, that you have to open a Nepalese Rupee account on the name of your company as soon as the papers are in progress at the Department of Industry. They force you to shift the money into this company account otherwise the entire process of registering your company stops straight in the track. This is the way to force you to spend that money in Nepal for what so ever you wanna do. So actually an Investor needs to keep two accounts in Nepal. Your private foreign currency account is safe and audit will not performed on it. The company account needs to be audited every year in order to maintain your business visa status.
Cheaper is to become a shareholder. Because it may change soon for the better or worse...one never knows...depending on which party coalition is ruling.
The last way to gain a visa for longer stay is that an international NGO ( a so called INGO) is ready to hire you for your professional skills. Mostly doctors, agriculture and other engineers, teachers and trainers make chance for long term jobs in Nepal.They will take care of your visa stuff and housing etc. To get a job is depending on your persistence to contact them and offer your services. There are websites to find where vacancies are shown...do your homework and you will find an opportunity!