Washing that keeps the fabric alive
Soft stretch fabrics like Butterluxe last far longer with a little care. Wash cold, on a gentle cycle, inside out. Cold water protects the elastane that gives the leggings their stretch and squat-proofing.
What to avoid
No fabric softener - it coats the fibres and reduces both softness and moisture-wicking over time. No high heat - hot washes and hot dryers break down elastane, which is what causes bagging and lost compression. Skip bleach entirely.
Drying
Air dry if you can - it is the single best thing for the lifespan of stretch activewear. If you must use a dryer, use low or no heat and pull them out slightly damp.
Pilling and snags
Wash activewear separately from towels, zips and Velcro, which cause pilling and snags. A mesh laundry bag helps. Done consistently, a pair keeps its shape and softness for years.