My apartment complex has a bike room too. In order to store a bike there residents are required to fill out a form identifying themselves and the bike’s make/model/color, etc. They then receive a numbered sticker to place on the bike so management can identify who it belongs to. Any bikes without stickers are removed at regular intervals. Residents are required to renew their stickers on an annual basis (Jan 1 but there is a one month grace period). This has kept out abandoned bikes and generally kept the room well managed but we don’t have enough spaces to meet demand 