There are four major factors and three of them have already been mentioned: the current trading price of the underlying commodity futures, the amount of time remaining until expiration, and the option's strike price. A fourth variable is the volatility of the markets.

Time to expiration:
All else being equal, an option with more time until expiration commands a larger premium than an option with less time until expiration. The longer option provides more time for your price expectations to be realized.

Strike price:
in the case of call options, it stands to reason that the most valuable options are those which convey the right to buy at a low price. Thus, all else being equal, a call option with a low strike price costs more to purchase than a call option with a high strike price. It's just the opposite for put options. The most valuable puts are those that have a high strike price.

Volatility:
Again, all else being equal, option premiums are usually higher when the markets are volatile. Volatile markets are considered more likely to produce the price movements that can make options profitable to own.