You need terms so your customers know what they are getting into, and so you are compliant with the rules of your payment processors.
Warning: you can't use the URL 'terms'. That one is already used up by Simplero as the default terms page and if you do set it up, an infinite loop with 'Too many redirects' gets created. But you can still use, for example, /terms-and-conditions instead :)
For GDPR terms check out our consent guide