The ladies put the sticker on it so that others will know we paid for it.
The cashier put the tape on it so that people will know we didn't steal it.
ーThe lady put the sticker on it so that others will know we paid for it.
「お金を払ったのがわかるように、レジのおばちゃんがシールを貼ってくれたんだよ。」
put the sticker on ... で「…にテープを貼る」
pay for ... で「…の代金を払う」
ーThe cashier put the tape on it so that people will know we didn't steal it.
「盗んでいないのがわかるように、レジの人がテープを貼ってくれたんだよ。」
put the tape on ... で「…にテープを貼る」
steal ... で「…を盗む」
ご参考まで!