Marcofromthenetherlands www.surfspot.nl has been known to provide expiring serial numbers. My understanding is the license they are selling you is for a period of time. Please contact www.surfspot.nl if you believe you have purchased a perpetual license to Design and Web Premium CS6.
If you wish to purchase a new license for CS6, or compare prices, you can do so at Creative Suite 6. If the price is significantly different then I would recommend verifying the return policy of the organization you are making the purchase from prior to proceeding.