We don't offer replacement keys at this time, but they are generically available Reention keys, made be Reention. There are a few 3rd party websites that offer replacement Reention keys for Reention battery systems. Here is one of the popular choices for ordering replacement keys: https://flx.bike/products/keys
Choose the "attack" option and message them the 3-digit lock cylinder number in order notes to get those keys.
They do not need to know what brand bike you have, as long as you are ordering keys from a Reention supplier.
Lock cylinder number location is shown below: