YES, you should, especially if you’re an employee and certainly if there’s a trade union branch at your workplace and you should do so for a variety of reasons, from personal to political.
Membership will give you protection if things go wrong and provide other material benefits. It will enable you to work with others to make your workplace safer and better. And it is the means by which you can, collectively, protect your wages and secure an improvement in your standard of living.
As Marx himself argued a century and a half ago, in Wages, Price and Profit, the wages struggle is very important. Without it wages would automatically sink to the minimum level required to sustain the individual worker and guarantee the reproduction of labour power. Without it, all workers would be much worse off.
And trades unions are an important vehicle for political change.