There are a lot of synonim of souvenir such as : gift, memento, relic, trophy, memorials, reminder, token and remembrance. You can use those words depends on the situation.
A souvenir (from French, meaning "a remembrance or memory"), memento, keepsake, or token of remembrance is an object a person acquires for the memories the owner associates with it. A souvenir can be any object that can be collected or purchased and transported home by the traveler as a memento of a visit.
There are many words which are like souvenir, we have words like trophy, rememberance or even gifts, the synonym for souvenir is hard to find because it sound different.
The word souvenir is a word that is often used to describe a gift or piece ofabilia that is not usually available for purchase..................................