The use of the pronoun 'it' is called an 'empty' object/subject. We use it as a meaningless subject with expressions that refer to time, weather, temperature, distances, or just the current situation. In the sentence "I like it here", 'it' refers to the situation or the conditions. For example: It's ten o'clock. It's Monday again. It rained for three days. It's thirty degrees. It's ten miles to the nearest petrol station. It's terrible - everybody's got colds, and the central heating isn't working. Wasn't it lovely there! Ed is correct. "I like here" is not a complete clause/sentence. In your sentence "I like it here", the verb 'like' is a transitive verb which requires the object 'it'.

"I like here", without the "it", is not a correct construction. You need to use the other.