When you say sagging, but then mention creases when you smile are you referring to two different issues you're having or just the smile lines you're seeing being more predominant after your face is relaxed?
Smile lines don't necessarily mean your skin is sagging, it's just that muscle and area is being worked out more so the skin is settling into the fine line/wrinkle zone.
Sagging would be the loss of elasticity to where you notice the skin is drooping and maybe feeling softer and more loose.
Look for products that contain peptides as peptides help plump, firm, and tone areas. Peptides sink into the skin and in gaps/areas where skin is missing collagen or elastin, they fill in the gaps and swell up to increase volume in those areas.
Other ingredients that help to plump skin up are humentacts, which help to bind moisture to the skin as moisturized skin shows fine lines less. Humectants like royal jelly, hyaluronic acid, and sodium hyaluronate are some to look for in skin care products.
Studio Gear (Ulta/Macys) has a treatment called Revisionist that I've seen work WONDERS! It's a peptide infused cream that can be used on the face and eye area to treat loss of elasticity, plump, firm, depuff, and soften fine lines and wrinkles. It gives instantaneous results as well as sink deeper to help repair the skin. The best way to apply is on a clean/toned face, tapp the product into areas of concern (smile lines, crows feet, forehead wrinkles, sagging lids, undereye bags, lines around the lips, and even on the neck) and let it sink in for a minute or two before applying your moisturizer.
Murad, Peter Thomas Roth, DDF, and many other lines make products/serums to treat issues like this, but price point-wise and for being able to get the job of face AND eyes taken care of, Studio Gear is the best I've come across.
Answered[ Edited ]
I use a gel moisturizer all over face and neck, Clinique's intense moisture (the pink stuff), and then follow up with pure frankincense essential oil. Actually I use a few drops of the frankincense oil mixed with a couple of drops of lavender essential oil and a couple of drops of jojoba oil. Lavender is gentle and calming. Jojoba is a liquid wax that greatly resembles the natural oils in skin and fills in fine lines for a smooth finish, and frankincense is the best thing ever. It firms and tones and heals skin, plus it "sets" fairly quickly into a smooth non-greasy layer on your skin. It feels like you're slathering a bunch of oil on your face and neck, but a minute or two later you're ready for sunscreen and whatever makeup you use. I use it at night too.
I use the Indian variety of pure frankincense essential oil that you can find online for $3 for a 1/2 ounce. That should last you a few weeks, long enough to see what a wonderful substance it is.
Frankincense oil gives me a firm jaw line again (I'm 56). I love the way my skin looks. It's a lot cheaper than creams, a little goes a long way, and it actually firms and tones sagging skin. Sagging ages you more than wrinkles and is harder to do anything about. Try pure frankincense essential oil. You'll be smooth and soft. Plus all your favorite Sephora cosmetics will look even better on you.