If you own the Student Book but lost the key, ask your school’s teacher coordinator for a clean answer sheet and scan it yourself. Then keep it privately on Google Drive.
If you're looking for these digital answer keys, follow this guide: Full Blast Plus 4 Student Book Answers Anyflip
If you need quick, occasional checks, the Anyflip version is perfect. If you need to grade papers rapidly or search for specific grammar points, you may find yourself wishing for a downloadable PDF format instead. If you own the Student Book but lost