I used an app to maketo use a certain app to make collages out of multiple photos into one.

また、

- I used to use a certain app to make photo collages.
- I've been using an app to make collages out of photos.

When I used ithe app recently, however, a lot of ads have been appeared.

また、日本語の翻訳から、

- Recently, when using this app, I started to see a lot of ads.

I looked for other good apps, but I and learned that Google Photo can do this.

I used an app to makcombine multiple photos into one.

Alt: I used an app to make a photo collage.