How long a veneer lasts depends on the material, the bonding surface, and everyday habits. The vast majority of ceramic veneers are still functioning after ten years; even so, every one will need replacing eventually. A veneer bonds far more reliably to enamel than to the dentin underneath, so over-preparation isn't just a loss of tooth structure, it's also a durability risk. That's the second reason to straighten crooked teeth first, if possible.
"Repairable" doesn't mean "as good as new." Fresh composite bonds far less well to material that's years old, a repaired spot stays a weak point. For minor edge damage, repair is still the right path; for larger damage, a new shell is.
Teeth grinding is the main risk factor: veneers come loose more often in people who grind, and they fail more often overall. A night guard mainly lowers the risk of the shell fracturing, provided it's actually worn.
Otherwise, a veneer needs no special care, just a few considerations: good oral hygiene, not biting into hard things with your front teeth, and your regular check-ups. With composite, also go easy on strongly staining foods. And: a veneer doesn't protect against decay, new cavities can form at a poorly maintained edge.
In the first few days after preparation, the tooth can be sensitive, especially to cold; this usually settles on its own. While the anaesthetic is still working, eat and drink carefully. Get in touch if a veneer chips or comes loose, an edge becomes sharp, or the tooth aches persistently.
If a ceramic veneer is replaced after years of use, the old shell can often be released with a dental laser via the bonding layer, without drilling it out, which protects the tooth; whether that works in your case depends on material and findings. Where else we use the laser is covered under Laser Dentistry.