Tempered Glass Lens Protectors (iPhone/iPad): They are not re-applicable, as they will lose their adhesiveness after removal. In order to ensure the glass protector stays on the lens, it uses a strong one-time adhesive.
Impact Protection Lens Protector (Android): It is re-applicable. When reapplying, it may attract dust. But that can easily be removed with the dust removal stickers that come with the product.