A membership within the student union costs 365 kr each year. You can renew it yourself on THS own website. You can get to the payment system directly at http://ths.kth.se/join. Older students only need to put in their personal identity number and the system will recognize the last membership. In the future, you will be able to renew your membership using ’My pages’.
You can also renew your membership by visiting the student office desk, Kårexpeditionen (KårX) in Nymble during their opening hours.