My working understanding is best expressed as "I will have fully earned", with "commeruero" being the first-person singular future perfect active indicative form of commereo. If I am far from the mark, I would really appreciate an explanation of why my interpretation is incorrect in non-technical terms, since I am not only uneducated in Latin, but also have little knowledge of the structure of languages in general - so it may be the case that even the meaning of the conjugation I have written is not as I understand it.
You're not entirely wrong, but it should be noted that commereo has negative connotations. For example, Ovid uses it with poenam ('earned the punishment'), and the comic poets coupled it frequently with culpam to mean something like "committed the crime." (I earned the blame = I did the deed.)
For 'earned' in a positive or neutral sense, you can use mereo and an adverb. This is the same word but without the com- prefix.
"I will have earned" is the English future perfect, which in Latin is formed by taking the perfect active stem and adding the future perfect endings, which you can find here.
In this case, the perfect active stem is meru-, and the first person singular indicative ending is -ero, giving you: meruero, "I will have earned."
For "fully," I don't think there's a prefix you can add to mereo to get you your desired meaning, but there are plenty of adverbs. A good one, in my opinion, is omnino, giving you the fuller sentence:
Omnino meruero, "I will have completely/fully earned"
You can even add whatever it is you have earned in the accusative case; if it's e.g. "praise," the sentence would be: laudam omnino meruero.