The process is different depending on if you use SignCut Pro 1 or SignCut Pro 2.

For SignCut Pro 1

You can go through our webshop by clicking Here, click on the period you want and then enter your license number and click purchase. That will take you to PayPal where you pay for your subscription. Once paid, the license will automatically be extended and only restarting SignCut should be necessary to update the subscription. If you prefer you can also visit our Livechat and request that we send a manual invoice from PayPal. Your extension will then be added when the payment has been received.

For SignCut Pro 2
For SignCut Pro 2 we have moved the purchase process inside the software. 
Start SignCut Pro 2 and click the account menu. There you have the option "Purchase extension". Select if you want to purchase a month or a year and if you wish to subscribe (recurring payment) which gives you a discount or if you want to make a single purchase. Once you've made your selection you click "Purchase". This will take you to PayPal where you complete the purchase. Once completed you click "Re-validate account" in the account menu in SignCut and the software will be updated with the new purchase.