Thailand is a member of the Berne Convention for the Protection of Literary and Artistic Works. Thus, any works creating in this country will get protection automatically. Through automatic protection, sometimes, it is very difficult for the copyright owners to prove their copyright works against infringers.
It is therefore strongly recommended to register your copyright works in Thailand to get the evidence proving your ownership.
Proof of copyright works is necessary at the time of copyright disputes and copyright infringement. Defending and proving the original copyright works is much more complicated, time consuming, costly than registration.