The Company leases certain office space, automobiles, computer hardware, and warehouse equipment under various non-cancelable operating leases. Some of these leases have renewal options. All of the Company’s leases expire at various times through August 2023. The Company also leases equipment under various month-to-month cancelable operating leases. For the years ended December 31, 2014 and 2013, total rent expense was approximately $3.9 million and $3.5 million, respectively.

Approximate future minimum rental commitments for non-cancelable operating leases (in thousands) are as follows:

The Company maintains supply agreements with its suppliers and manufacturers. Some of the supply agreements contain exclusivity clauses and/or minimum annual purchase requirements. In March 2006, the Company entered into a ten-year supply agreement to purchase plant-derived mineral nutrition products from IHT Health Products, Inc. (f.k.a. InB:Biotechnologies, Inc.). As of December 31, 2014, the Company is required to purchase an aggregate of $5.8 million through 2016.

The Company utilizes royalty agreements with individuals and entities to provide compensation for items relating to developed products, websites and email provided to our associates. The Company paid royalties of $0.3 million in each of 2014 and 2013.

The Company has non-cancellable employment agreements with certain executives. If the employment relationships with these executives were terminated, as of December 31, 2014, the Company would continue to be indebted to the executives for $0.7 million, payable through 2015.