[Deserion]

Now I'm not certain if this is possible, or if your car had an alarm (I suggest entering your VIN into one of the Porsche VIN decoders to check), but adding keyless back may be an option. I believe all Porsches of that vintage came with keyless, but it may have been a penny-pinching prior owner who decided to go without the remotes to save a buck on replacement.

You may be able to switch the keyblade and Immobilizer pellet from the old key into a new remote (about $145/each) to save from having a new keyblade cut and Immobilizer programmed to the instrument cluster. I'm not sure how the remote is programmed (if possible as a DIY like most Volkswagens I'm familiar with), or if the dealer/shop has to do that.