According to the current implementation, the user has to call .init(policy) explicitly before they want to validate for a specific policy which does not seem very elegant. Either this should be mentioned explicitly or the API can be modified to eliminate users to make mistakes which is much better.

const policySetter = require ('password-policy-setter');

const verificationCodePolicy = {
   size    : 6,
   lower   : false,
   upper   : true,
   numbers : false,
   splChar : false,
}
const signupPasswordPolicy = {
   size    : 15,
   lower   : 1,
   upper   : 1,
   numbers : 1,
   splChar : 1,
}

const inputVerificationCode = 'SECRET';
const inputSignupPassword = 'SecretP@assword'

policySetter.init(verificationCodePolicy);

if (!policySetter.satisfied(inputVerificationCode))
   throw new Error('Invalid verification code');

// ⚠️ explicity remeber to change policy as module keeps track of last set policy
policySetter.init(signupPasswordPolicy);

if (!policySetter.satisfied(inputSignupPassword))
   throw new Error('Invalid signup password');

Suggestion

I would suggest keeping the library stateless and delegating state handling to the user's application.

const PolicySetter = require ('password-policy-setter');
/* This forces the user to handle policy state and gets rid of global state management from the library*/

const verificationCodePolicySetter = new PolicySetter(verificationCodePolicy);
verificationCodePolicySetter.satisfied(inputVerificationCode);
verificationCodePolicySetter.findAnomaly(inputVerificationCode);

const signupPasswordPolicySetter = new PolicySetter(signupPasswordPolicy);
signupPasswordPolicySetter.satisfied(inputSignupPassword);
signupPasswordPolicySetter.findAnomaly(inputSignupPassword);

Another way could be to remove direct access to satisfied()/findAnomaly() and to force users to explicitly set policy every time they want to check some input.

policySetter.init(verificationCodePolicy).satisfied(inputVerificationCode);
policySetter.init(verificationCodePolicy).findAnomaly(inputVerificationCode);

policySetter.init(signupPasswordPolicy).satisfied(inputSignupPassword);
policySetter.init(signupPasswordPolicy).findAnomaly(inputSignupPassword);