Exclusively breastfeeding at 54 days is going very well, so you likely don't need that hospital formula at all. It was just given as a backup supply in case feeding didn't establish, and your baby clearly doesn't need it now.
Next Steps
Check the expiry date printed on the tin. If it's still sealed and within date, you can keep it aside as backup. If it's past date, has been opened, or looks worn, it's safest to discard it rather than use it later.
Health Tips
Only reach for formula if your baby stops gaining weight well or your own milk supply genuinely drops, not just because the tin is there. Please see your pediatrician at your next visit to confirm feeding and weight gain are on track.