Keeping left-over pan sauces longer?
First thing to try is freezing, possibly in ice cube trays (once frozen, transfer to freezer bag). Freezing has the advantage that you can be confident the food is still safe to consume.

Unfortunately, cornstarch-thickened sauces often don't hold up to freezing. A couple of approaches:


Thicken only after thawing. Takes more time reheating, but not much.
Try arrowroot or tapioca starch. You'll get a different look and slightly different texture than you're used to.
Use "modernist" ingredients for thickening, such as guar gum and/or xanthan gum. The texture is probably going to be different than what you're used to.


Your BBQ sauce is not only low-pH it is also high-sugar. Both reduce microbial growth. It'd be difficult to know how long your pan sauce would last in the fridge without measuring those, and possibly doing lab work.