Does amoxicillin expire in a ertain mount of time?

Yes. All drugs expire eventually. There should be an expiration date on your prescription. When in doubt, throw out anything greater than 1 year old.
Certainly. While some meds may be in a stable form and hold strength longer than others they all will expire eventually. Amoxicillin liquid preparations prescribed for kids often go bad in hours in a heated car, days at room temperature in 2 wks if refrigerated. Pills or capsules would have an expiration date listed on the prescription bottle.