Yes, but not for over two years. Don't worry about it.
We provide you with a Genotek PG-100 swab. Every swab has an expiration date of 28 months from the date that you can see on the swab (e.g.31001602132502). After the saliva sample has been collected, the swab tube is sealed and the swab is soaked in the stabilizer liquid; we can still extract the DNA for testing for up to a year. However, we recommend sending the sample as soon as you can providing that there are no specific reasons to hold onto the swab.
In any case, sufficiently sampling the dog's DNA is the most important step. Get lots of slobber! 💦