I keep a photo album because it's fun and to remember the happy moments in my life.

I think it should be I keep many photos in the album so that I could remember happy moments and have fun.

The indefinite article would be used in this case if, for example, you were telling someone about a photo album you had at home. If you were showing someone the album, or if you had previously been speaking about it, then you would probably use the definite article. Hope that helps :)

Thank you,Nicole. Why did you put the indefinite article before "album"?

I keep photos in an album to have fun and remember happy moments.