Opinion on long term lease

[L. Brown]

Hello BP Community, I currently own a duplex that I house hack. The tenant would like to extend her lease for 18 months. At face value this seems to be a good move- she pays on time, guarantees I will have a tenant when I move out in a year, and she's a pretty good tenant. Is there is anything I should be wary or mindful of in going into a long term lease? Thanks!