Yes, memory there is upgradeable to 8GB DDR3. Also, please be aware in advance that you will need to enter sudo amdconfig --initial after install what required and before restarting your system. If and when ready you might want to start here: Installation failed - please help - #2 by mladen, as I do hope for you that this related post/thread might help there indeed.
Another request of mine before you start anything, would be: with time please replace your original HDD to SSD as otherwise everything will very likely fail or rather usability might be questionable during daily usage (and while PureOS Live image USB Flash drive runs well there).