Once the bottle of coating is opened, the curing process begins, even if you put the cap back on tightly. Once opened, you should use the coating within one month's time.
Please be sure to use all coatings as soon as you can from the time you receive them.
All coatings have a limited shelf life due to the chemical nature of how they crystallize. Look to use coatings within 4-6 months of receiving them (less if bottle is opened).