Individual landlords have a right not to renew rent-stabilized leases if they can prove their intentions to employ the units for "personal use." Legally, personal use includes property owners or members of their immediate families. A variation on this theme is the landlord who claims to want a unit for business use, such as turning your apartment into a management office. In this instance, the landlord must persuade the Division of Housing and Community Renewal ("DHCR") to authorize eviction of a residential tenant for business purposes. Once again, there is a legal obligation to supply evidence to support that position, but it can be a legitimate threat to your lease. Fortunately, it's not quite a cut and dried issue. The landlord's proof can be refuted. If you find yourself in this situation, it's not advisable to attempt to represent yourself, as handling various aspects of these cases can be very complex. Note that if your building or apartment is owned by a corporation or partnership, the landlord cannot seize the unit for personal use.
Attention New York City Tenants: Get more information on personal use suits at the McAdams Law main site here.