Under Thai law, foreigners are not allowed freehold ownership of land but are allowed to own any structures built upon the land. This means a long-term lease will be registered and the structures (i.e. villa) will be transferred to the buyer. Both the registration of the lease and the transfer of the villa are done at the Land Office.
The land lease is initially registered for 30 years, which can be renewed for 2 consecutive periods of 30 years each. This means the total lease period is effectively 90 years.