For the merchant, it’s income you can count on (and on the customer coming back.) For the regular buyer, it’s a better deal both financially and as a convenience.
Offer your frequent regular clients to pre-pay a certain monthly amount (based on their past records) in exchange for better deals and special VIP service (for instance they can phone in or send an email with their requests and a personal shopper will handpick and prepare them for shipping or pick up.)
No time commitment, use for anything.
Buy the VIP card, pre-load with money and use it for all the attractions in a given city or country, without having to make a commitment to a visit time. Just go there and use the card. You can always top it up.