If a Thai leases, via a registered land office leases, for say 5, 10, 15,... years etc, and the plot of land leased includes a house built on it, does the Thai need a rental property license?

I think you will find there is no such document. The lease is the property rental agreement, record, permission, licence etc. If someone rents a property, thats it, never heard of other licenses.

 

Are you possibly asking whether the landlord needs some sort of licence ? Again, there is no license to rent or rent out a property.