How can i upgrade from final cut express to pro?

Final Cut Express 4 and Final Cut Pro 7 were dropped by Apple over 4 years ago and are unlikely to work properly on the latest Macs running Yosemite.

Both apps are very similar and there is absolutely no advantage in upgrading unless FCP 7 has some special tool/feature that you need.

The only way to buy them now is on the second hand market like eBay.

However, if you want to move from 20th. century technology into the 21st. century, you should go for Final Cut Pro X which is designed for all the latest camera formats and operating systems.

If you mean software upgrade there is no actual upgrade from Final Cut Express to Final Cut Pro 7 or Final Cut Pro X. You have to purchase the Pro version. It's always been that way.

If you mean can you use FCE projects in Final Cut Pro, FCE projects can be opened & used in Final Cut Pro 7 ... but not in FInal Cut Pro X.