This is a regular verb. It follows the conjugation pattern of the verb comer.
This verb is much more common in European Portuguese in the sense of to put. In Brazilian Portuguese, colocar or pôr are often preferred in neutral contexts.
Present:
O Miguel mete o livro na mochila.
Miguel puts the book in the bag.
Preterite:
A Ana meteu as chaves na gaveta.
Ana put the keys in the drawer.
Conditional:
O Tiago meteria isso em outra caixa.
O Tiago meteria isso noutra caixa.
Tiago would put that in another box.