Trademark registration offers a very effective way of stopping copycats from stealing your brand identity and damaging your reputation. When your brand becomes well known, more and more people will attempt to copy it. The more countries you register your trademark in, the broader protection you get. Your trademark is only valid in those countries where you register it. Since the uniqueness of your brand is one of your biggest assets, it is always worth registering a trademark to protect it.
You might consider registering your trademark in countries where you have the biggest customer base and the most sales. You can always start with one country and expand your protection later. You don't necessarily need a trademark registration in every country. Still, it is beneficial to cover the major markets, such as the US, UK, and EU, depending on where you are commercially active.
To sum it up, a trademark is definitely worth it. It does not only protect you against copycats of your brand, but it also eliminates the possibility of a third party contacting you and asking you to stop using your brand name completely because they registered it first.
You can find more ways in which a trademark can prove helpful to you in our article 10 reasons for registering a trademark