You can live permanently in a mobile home as long as it's setup properly and you have the electricity, running water, sewer etc all hooked up.
Mobiles homes are meant to be lived in long term like a traditional house although some mobile homes wear out faster than traditional homes and may require more upkeep.
But with proper upkeep the mobile home can last several years.
Some mobile homes are 40 to 50 years old and are still being lived in and today's mobile homes are also built better than the older mobile homes were.
You do need a permit to put a mobile home on your property in some locations although in other locations you may be able to put the mobile home on your property without needing permits.
It can depend on the town, county, zoning etc.
If you live in a county that doesn't require permits, then you can often place a mobile home on your property without permits.
You cannot put a mobile home on just any land.
When deciding on a mobile home you have to ensure that the land you want to put the mobile home on is zoned for residential use and the land has no deed restrictions that restrict mobile homes.
You also have to ensure that the mobile home also meets zoning regulations and all local building codes.
Some lands have private covenants or even deed restrictions which can be placed on the property.
For example if you buy land in an HOA they will not allow mobile homes unless it's a mobile home HOA community.
The land for mobile homes must be zoned for mobile homes to be able to put a mobile home on the land.
In some places the land may not have any restrictions and you can place the mobile homes on these lands but you have to make sure they allow mobile homes.
If you buy land that is way out in the woods then you can likely easily put a mobile home on that type of land.
And in some places that restrict mobile homes you can often live temporarily in the mobile home or RV while actively building a site built home.