Please find free do it yourself programming instructions below
Works for the following
1991, 1992, 1993, 1994, 1995 and 1996 Buick Century keyless remote system

IMPORTANT: Before entering programming mode, have in possession all of the transmitters you will be using on the vehicle. Once you program the transmitter, all previous codes will be erased from the memory. The other transmitters will not be functional until you program the transmitters again. You can program up to 2 remotes
1. Access programming connector wire (a single black/white wire located behind panel in RH trunk)
2. Connect programming connector wire to the ground (any metal element in your vehicle)
3. Door locks should lock and unlock to indicate programming mode active
4. To program remotes proceed as follows
5. Press any button on remote transmitter
6. Door locks should lock and unlock to indicate programming of this remotes
7. Repeat 5 for additional remote
8. Disconnect programming connector wire from ground to exit programming mode
If you have any questions please contact us at 866-690-4308 or email at customercare@carandtruckremotes.com. If your remote does not program, you most likely need to order another remote to replace a broken one.
To order a remote or for more information, click on the link below:
https://www.carandtruckremotes.com/buick-remotes-century-remotes.html