I looked at my closest library’s website, online-only lasts for 90 days. For a full card it states proof of residency or A form of identification that has your current , permanent address on it as a requirement (of which I don’t have the listed examples).

Although I also depend on the weather being nice (it has been hot lately) to ride my bike to the town the library is in, so not too keen on the idea of needing to return stuff anyway.