Even if the trademark has already been in use for a long time, it should still be registered. In Malaysia the first party to use the trademark has more rights than the first party that filed the trademark application. Better be safe than sorry. Don’t pass this off register your trademark.
Second important thing to know is that a trademark registration does not cover all goods and services. It is important to register the trademark under the correct class of goods and services.
And lastly registering a trademark in one country does not give universal trademark rights. The trademark rights are territorial and do not apply to newer territories. If you have trademark in Malaysia does not mean you have trademark rights in Indonesia, Thailand, Singapore etc.