The sticker must be ______ your windshield.

Affix (verb transitive)
- affix something (to) (আনুষ্ঠানিক) আযুক্ত/যুক্ত/সংযুক্ত করা; জুড়ে দেওয়া।
- affix a seal/stamp to a document; affix one’s signature to an agreement.
যেমন: 
She affixed a stamp to the envelope.
The sticker must be affixed to your windshield.

Source: 
1. Accessible Dictionary by Bangla Academy
2. Cambridge Dictionary