Is to cherish his memory is two correct grammar?

The phrase "to cherish his memory" is grammatically correct. It is an infinitive phrase acting as the subject of the sentence.

Here are some examples of how it could be used in a sentence:

* It is a privilege to cherish his memory.

* To cherish his memory is all we can do now.

However, if you are asking if "to cherish his memory is two" is grammatically correct, then the answer is no. It doesn't make sense grammatically or logically. "Two" is a number and does not relate to cherishing someone's memory.